Remove usql

[dveeden]

What problem does this PR solve?

close #2588

What is changed and how it works?

Replaces usql (which brings many indirect dependencies) with printing a line that prints the commandline options for MySQL Client.

This fixes:

• the large number of indirect dependencies of usql
• the usql behaviour not matching the behavior of TiDB docs (as it follows postgres behavior)
• tiup client for playground having a different behavior and experience as a tiup cluster or k8s deployed cluster.

We could:

• Directly call mysql
• Detect what clients (MySQL Client, MySQL Shell, mycli, usql, DBeaver, etc) are installed and print what is applicable

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 is 1.13636% with 87 lines in your changes missing coverage. Please review.
✅ Project coverage is 40.60%. Comparing base (e446891) to head (68360f3).
⚠️ Report is 5 commits behind head on master.

⚠️ Current head 68360f3 differs from pull request most recent head 758d560

Please upload reports for the commit 758d560 to get more accurate results.

Files with missing lines	Patch %	Lines
pkg/cluster/manager/upgrade.go	0.00%	19 Missing ⚠️
pkg/cluster/spec/pd.go	0.00%	15 Missing ⚠️
pkg/cluster/operation/upgrade.go	0.00%	13 Missing ⚠️
components/client/main.go	0.00%	9 Missing ⚠️
pkg/cluster/api/pdapi.go	0.00%	8 Missing ⚠️
pkg/cluster/operation/action.go	0.00%	3 Missing ⚠️
pkg/tidbver/tidbver.go	0.00%	3 Missing ⚠️
pkg/cluster/spec/cdc.go	0.00%	2 Missing ⚠️
pkg/cluster/spec/scheduling.go	0.00%	2 Missing ⚠️
pkg/cluster/spec/tikv.go	0.00%	2 Missing ⚠️
... and 8 more

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2596      +/-   ##
==========================================
- Coverage   40.97%   40.60%   -0.37%     
==========================================
  Files         363      363              
  Lines       37683    38216     +533     
==========================================
+ Hits        15440    15517      +77     
- Misses      20327    20781     +454     
- Partials     1916     1918       +2     

Flag	Coverage Δ
tiup	33.89% <ø> (ø)
unittest	16.61% <1.14%> (-0.03%)	⬇️

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[dveeden]

/cc @xhebox @ottok

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