task: implement parallel concurrency limit

[AstroProfundis]

What problem does this PR solve?

Close #649

What is changed and how it works?

• Add a concurrency threshold in context
• Implement concurrency limiter in task.Execute for parallel tasks
• Add a global argument to tiup-cluster and tiup-dm to let user set the concurrency

The concurrency is default to 5 as set in command line argument, and is the number of CPU threads for task if not set.

Check List

Tests

• Manual test (add detailed scripts or steps below)

Code changes

• Has exported function/method change
• Has exported variable/fields change

Related changes

• Need to update the documentation

Release notes:

task: implement parallel concurrency limit

[codecov-commenter]

Codecov Report

Merging #1420 (194a8f9) into master (e5e1b46) will increase coverage by 15.50%.
The diff coverage is 55.76%.

@@             Coverage Diff             @@
##           master    #1420       +/-   ##
===========================================
+ Coverage   25.39%   40.90%   +15.50%     
===========================================
  Files         266      291       +25     
  Lines       20628    22525     +1897     
===========================================
+ Hits         5238     9213     +3975     
+ Misses      14586    11828     -2758     
- Partials      804     1484      +680     

Flag	Coverage Δ
dm	24.08% <54.90%> (?)
integrate	32.24% <54.90%> (+16.77%)	⬆️
playground	13.73% <0.00%> (?)
tiup	15.46% <0.00%> (-0.01%)	⬇️
unittest	21.73% <6.25%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
components/dm/command/import.go	19.04% <0.00%> (ø)
pkg/cluster/ansible/config.go	0.00% <0.00%> (ø)
pkg/cluster/ansible/service.go	3.53% <0.00%> (ø)
pkg/cluster/manager/basic.go	50.48% <0.00%> (+50.48%)	⬆️
pkg/cluster/manager/check.go	0.00% <0.00%> (ø)
pkg/cluster/manager/cleanup.go	0.00% <0.00%> (ø)
pkg/cluster/manager/deploy.go	59.80% <0.00%> (+59.80%)	⬆️
pkg/cluster/manager/destroy.go	30.98% <0.00%> (+30.98%)	⬆️
pkg/cluster/manager/patch.go	0.00% <0.00%> (ø)
pkg/cluster/manager/reload.go	60.65% <0.00%> (+60.65%)	⬆️
... and 165 more

---

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[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• lucklove

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[lucklove]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: d802b89

[AstroProfundis]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 194a8f9