feature:add a cli command to ha pattern (HA third part)

[yunfeiyanggzq]

Ⅰ. Describe what this PR did

this part is branch of #741 should be merged after it
active supernode uses the ha_mgr to send dfget's request to standby supernode

Ⅱ. Does this pull request fix one issue?

Ⅲ. Why don't you add test cases (unit test/integration test)? (你真的觉得不需要加测试吗？)

Ⅳ. Describe how to verify it

Ⅴ. Special notes for reviews

my pr will be submitted as follows

• 1.implement a ha_mgr to implement active/standby switch-----done
• 2.add a cmd config to config ha ,use ha_mgr to change supernode status between active and standby ----done
• 3.add new interface to ha_mgr(active supernode send a copy of all the dfget's request to standby supernode to implement state synchronization ) ----done
• 4.modify dfget's code(dfget can go on it's work after the active supernode is off)
• 5.implement the vip

[codecov-io]

Codecov Report

Merging #758 into master will decrease coverage by 1.16%.
The diff coverage is 7.5%.

@@            Coverage Diff             @@
##           master     #758      +/-   ##
==========================================
- Coverage   39.66%   38.49%   -1.17%     
==========================================
  Files         109      109              
  Lines        6429     6660     +231     
==========================================
+ Hits         2550     2564      +14     
- Misses       3671     3882     +211     
- Partials      208      214       +6

Impacted Files	Coverage Δ
cmd/dfdaemon/app/version.go	75% <ø> (+5.76%)	⬆️
cmd/supernode/app/version.go	75% <ø> (+5.76%)	⬆️
supernode/daemon/mgr/dfgettask/manager.go	47.74% <ø> (ø)	⬆️
supernode/server/0.3_bridge.go	0% <0%> (ø)	⬆️
supernode/daemon/mgr/task/manager_util.go	16.86% <0.78%> (-7.44%)	⬇️
cmd/supernode/app/root.go	61.06% <100%> (+2.18%)	⬆️
supernode/daemon/mgr/peer/manager.go	77.41% <60%> (-1.24%)	⬇️
supernode/server/server.go	41.37% <60%> (+0.63%)	⬆️
supernode/daemon/mgr/task/manager.go	24.22% <7.89%> (-5.94%)	⬇️
supernode/config/config.go	43.42% <9.67%> (-23.25%)	⬇️
... and 4 more

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[pouchrobot]

ping @yunfeiyanggzq
Conflict happens after merging a previous commit.
Please rebase the branch against master and push it back again. Thanks a lot.