processor: input: output: organize initialization sequence for processor

[cosmo0920]

In #7071, users reported SEGV when including rewrite_tag plugin within processor stack.
This can be occurred with initialization order for filter plugins on the stack.
All of plugins must be initialized through flb_engine_start to initialize event loop and storage and other required instances correctly.
This PR fixes the invalid initialization of processor stack which includes rewrite_tag plugin.

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Testing
Before we can approve your change; please submit the following in a comment:

• Example configuration file for the change

pipeline:
    inputs:
      - name: dummy
        tag: test-tag.raw
        dummy: '{"tool": "fluent", "sub": {"s1": {"s2": "bit"}}}'

        processors:
          logs:
            - name: modify
              match: test-tag.*
              add: hostname monox
            - name: rewrite_tag
              match: test-tag.*
              rule: $tool ^(fluent)$  from.$TAG.new.$tool.$sub['s1']['s2'].out false
              emitter_name: re_emitted

    outputs:
      - name: stdout
        match: '*'

        processors:
          logs:
            - name: lua
              call: add_field
              code: |
                  function add_field(tag, timestamp, record)
                     new_record = record
                     new_record["output"] = "new data"
                     return 1, timestamp, new_record
                  end

• Debug log output from testing the change

Fluent Bit v2.1.3
* Copyright (C) 2015-2022 The Fluent Bit Authors
* Fluent Bit is a CNCF sub-project under the umbrella of Fluentd
* https://fluentbit.io

[2023/05/16 16:38:41] [ info] Configuration:
[2023/05/16 16:38:41] [ info]  flush time     | 1.000000 seconds
[2023/05/16 16:38:41] [ info]  grace          | 5 seconds
[2023/05/16 16:38:41] [ info]  daemon         | 0
[2023/05/16 16:38:41] [ info] ___________
[2023/05/16 16:38:41] [ info]  inputs:
[2023/05/16 16:38:41] [ info]      dummy
[2023/05/16 16:38:41] [ info] ___________
[2023/05/16 16:38:41] [ info]  filters:
[2023/05/16 16:38:41] [ info] ___________
[2023/05/16 16:38:41] [ info]  outputs:
[2023/05/16 16:38:41] [ info]      stdout.0
[2023/05/16 16:38:41] [ info] ___________
[2023/05/16 16:38:41] [ info]  collectors:
[2023/05/16 16:38:41] [ info] [fluent bit] version=2.1.3, commit=815496155e, pid=1717500
[2023/05/16 16:38:41] [debug] [engine] coroutine stack size: 24576 bytes (24.0K)
[2023/05/16 16:38:41] [ info] [storage] ver=1.2.0, type=memory, sync=normal, checksum=off, max_chunks_up=128
[2023/05/16 16:38:41] [ info] [cmetrics] version=0.6.1
[2023/05/16 16:38:41] [ info] [ctraces ] version=0.3.0
[2023/05/16 16:38:41] [ info] [input:dummy:dummy.0] initializing
[2023/05/16 16:38:41] [ info] [input:dummy:dummy.0] storage_strategy='memory' (memory only)
[2023/05/16 16:38:41] [debug] [dummy:dummy.0] created event channels: read=21 write=22
[2023/05/16 16:38:41] [debug] [filter:modify:modify.0] Initialized modify filter with 0 conditions and 1 rules
[2023/05/16 16:38:41] [ info] [input:emitter:re_emitted] initializing
[2023/05/16 16:38:41] [ info] [input:emitter:re_emitted] storage_strategy='memory' (memory only)
[2023/05/16 16:38:41] [debug] [emitter:re_emitted] created event channels: read=23 write=24
[2023/05/16 16:38:41] [debug] [stdout:stdout.0] created event channels: read=25 write=26
[2023/05/16 16:38:41] [ info] [output:stdout:stdout.0] worker #0 started
[2023/05/16 16:38:41] [debug] [router] match rule dummy.0:stdout.0
[2023/05/16 16:38:41] [debug] [router] match rule emitter.1:stdout.0
[2023/05/16 16:38:41] [ info] [sp] stream processor started
[2023/05/16 16:38:41] [debug] [input chunk] update output instances with new chunk size diff=65
[2023/05/16 16:38:42] [debug] [task] created task=0x7f69b0047660 id=0 OK
[2023/05/16 16:38:42] [debug] [output:stdout:stdout.0] task_id=0 assigned to thread #0
[0] from.test-tag.raw.new.fluent.bit.out: [[1684222721.442910671, {}], {"sub"=>{"s1"=>{"s2"=>"bit"}}, "tool"=>"fluent", "output"=>"new data", "hostname"=>"monox"}]
[2023/05/16 16:38:42] [debug] [input chunk] update output instances with new chunk size diff=65
[2023/05/16 16:38:42] [debug] [out flush] cb_destroy coro_id=0
[2023/05/16 16:38:42] [debug] [task] destroy task=0x7f69b0047660 (task_id=0)
[2023/05/16 16:38:43] [debug] [task] created task=0x7f69b0046be0 id=0 OK
[2023/05/16 16:38:43] [debug] [output:stdout:stdout.0] task_id=0 assigned to thread #0
[0] from.test-tag.raw.new.fluent.bit.out: [[1684222722.442936182, {}], {"sub"=>{"s1"=>{"s2"=>"bit"}}, "tool"=>"fluent", "output"=>"new data", "hostname"=>"monox"}]
[2023/05/16 16:38:43] [debug] [input chunk] update output instances with new chunk size diff=65
[2023/05/16 16:38:43] [debug] [out flush] cb_destroy coro_id=1
[2023/05/16 16:38:43] [debug] [task] destroy task=0x7f69b0046be0 (task_id=0)
^C[2023/05/16 16:38:44] [engine] caught signal (SIGINT)
[2023/05/16 16:38:44] [debug] [task] created task=0x7f69b0046e00 id=0 OK
[2023/05/16 16:38:44] [debug] [output:stdout:stdout.0] task_id=0 assigned to thread #0
[2023/05/16 16:38:44] [ warn] [engine] service will shutdown in max 5 seconds
[2023/05/16 16:38:44] [ info] [input] pausing dummy.0
[0] from.test-tag.raw.new.fluent.bit.out: [[1684222723.442939758, {}], {"sub"=>{"s1"=>{"s2"=>"bit"}}, "tool"=>"fluent", "output"=>"new data", "hostname"=>"monox"}]
[2023/05/16 16:38:44] [debug] [out flush] cb_destroy coro_id=2
[2023/05/16 16:38:44] [debug] [task] destroy task=0x7f69b0046e00 (task_id=0)
[2023/05/16 16:38:44] [ info] [engine] service has stopped (0 pending tasks)
[2023/05/16 16:38:44] [ info] [input] pausing dummy.0
[2023/05/16 16:38:44] [ info] [output:stdout:stdout.0] thread worker #0 stopping...
[2023/05/16 16:38:44] [ info] [output:stdout:stdout.0] thread worker #0 stopped

• Attached Valgrind output that shows no leaks or memory corruption was found

==1717689== 
==1717689== HEAP SUMMARY:
==1717689==     in use at exit: 0 bytes in 0 blocks
==1717689==   total heap usage: 2,992 allocs, 2,992 frees, 3,248,250 bytes allocated
==1717689== 
==1717689== All heap blocks were freed -- no leaks are possible
==1717689== 
==1717689== For lists of detected and suppressed errors, rerun with: -s
==1717689== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

If this is a change to packaging of containers or native binaries then please confirm it works for all targets.

• Run local packaging test showing all targets (including any new ones) build.
• Set ok-package-test label to test for all targets (requires maintainer to do).

Documentation

• Documentation required for this feature

Backporting

• Backport to latest stable release.

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Fluent Bit is licensed under Apache 2.0, by submitting this pull request I understand that this code will be released under the terms of that license.