tiup: support run components without tiup

[nexustar]

What problem does this PR solve?

What is changed and how it works?

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]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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[codecov-commenter]

Codecov Report

Patch coverage: 22.37% and project coverage change: -0.07% ⚠️

Comparison is base (78092c0) 55.81% compared to head (17ff699) 55.74%.
Report is 1 commits behind head on master.

❗ Current head 17ff699 differs from pull request most recent head 12d9930. Consider uploading reports for the commit 12d9930 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2265      +/-   ##
==========================================
- Coverage   55.81%   55.74%   -0.07%     
==========================================
  Files         321      323       +2     
  Lines       34022    34096      +74     
==========================================
+ Hits        18989    19006      +17     
- Misses      12761    12817      +56     
- Partials     2272     2273       +1     

Flag	Coverage Δ
tiup	15.90% <22.37%> (+0.03%)	⬆️
unittest	22.60% <33.33%> (+0.02%)	⬆️

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

Files Changed	Coverage Δ
pkg/environment/env.go	52.76% <8.82%> (-8.31%)	⬇️
cmd/unlink.go	23.08% <23.08%> (ø)
cmd/link.go	42.86% <42.86%> (ø)
cmd/root.go	48.67% <100.00%> (+0.46%)	⬆️

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2023-08-25 09:37:07.454662657 +0000 UTC m=+1487792.003678645: ☑️ agreed by srstack.
• 2023-08-25 11:04:32.604375336 +0000 UTC m=+1493037.153391320: ✖️🔁 reset by nexustar.
• 2023-08-25 14:37:42.499412004 +0000 UTC m=+1505827.048427991: ☑️ agreed by kaaaaaaang.

[kaaaaaaang]

/merge

[kaaaaaaang]

/lgtm