treat version as string instead of float when compare

[ghoshh]

What problem does this PR solve?

ref #2654

What is changed and how it works?

add a function to compare versions by splitting the version into integers to avoid the case like 8.4 > 8.10.

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

This pull-request has been approved by:
Once this PR has been reviewed and has the lgtm label, please assign bb7133 for approval. For more information see the Code Review Process.
Please ensure that each of them provides their approval before proceeding.

The full list of commands accepted by this bot can be found here.

Details

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[ti-chi-bot]

Welcome @ghoshh! It looks like this is your first PR to pingcap/tiup 🎉

[pingcap-cla-assistant]

All committers have signed the CLA.

[lance6716]

1. no need to be public function
2. add unit test to verify its behaviour

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 39.13%. Comparing base (e525ada) to head (0048aa5).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2656      +/-   ##
==========================================
+ Coverage   38.99%   39.13%   +0.13%     
==========================================
  Files         356      356              
  Lines       36898    36912      +14     
==========================================
+ Hits        14388    14443      +55     
+ Misses      20709    20665      -44     
- Partials     1801     1804       +3     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.