tiup: refactor help

[nexustar]

What problem does this PR solve?

• close error when tag name is the same as component name #1829 wrong exit code #1830

What is changed and how it works?

• refactor tiup help. remove hack, just use cobra help or simply passthrough -h/--help to component
• not parse flags on root command, add a switch instead

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Code changes

• Has exported function/method change
• Has exported variable/fields change
• Has interface methods change
• Has persistent data change

Side effects

• Possible performance regression
• Increased code complexity
• Breaking backward compatibility

Related changes

• Need to cherry-pick to the release branch
• Need to update the documentation

Release notes:

NONE

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• srstack

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[codecov-commenter]

Codecov Report

Merging #1831 (7336297) into master (6e8d6e2) will decrease coverage by 7.66%.
The diff coverage is 58.93%.

@@            Coverage Diff             @@
##           master    #1831      +/-   ##
==========================================
- Coverage   52.71%   45.06%   -7.66%     
==========================================
  Files         307      306       -1     
  Lines       35076    34975     -101     
==========================================
- Hits        18490    15759    -2731     
- Misses      14419    17336    +2917     
+ Partials     2167     1880     -287     

Flag	Coverage Δ
cluster	28.63% <ø> (-12.47%)	⬇️
dm	24.55% <ø> (-0.16%)	⬇️
playground	12.52% <ø> (-0.09%)	⬇️
tiup	14.15% <58.93%> (-0.43%)	⬇️
unittest	21.26% <26.79%> (-0.08%)	⬇️

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

Impacted Files	Coverage Δ
cmd/root.go	56.36% <58.93%> (-4.85%)	⬇️
pkg/cluster/template/config/config.go	0.00% <0.00%> (-100.00%)	⬇️
pkg/cluster/template/scripts/scripts.go	0.00% <0.00%> (-100.00%)	⬇️
pkg/cluster/template/scripts/tiflash.go	0.00% <0.00%> (-77.94%)	⬇️
pkg/cluster/operation/systemd.go	0.00% <0.00%> (-75.00%)	⬇️
pkg/cluster/template/systemd/tispark.go	0.00% <0.00%> (-65.71%)	⬇️
pkg/cluster/task/limits.go	0.00% <0.00%> (-65.22%)	⬇️
pkg/cluster/template/scripts/tispark.go	0.00% <0.00%> (-63.79%)	⬇️
pkg/cluster/task/sysctl.go	0.00% <0.00%> (-63.64%)	⬇️
pkg/cluster/manager/check.go	5.20% <0.00%> (-63.59%)	⬇️
... and 80 more

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[AstroProfundis]

/merge

[ti-chi-bot]

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

Commit hash: 7336297