Add command to see the unresolved transactions

[GuptaManan100]

Description

This PR adds the syntax and implementation for reading all pending unresolved atomic transactions. The two following types of queries are supported -

1. show unresolved transactions for ks - This command gets all the unresolved transactions in the keyspace ks.
2. show unresolved transactions - This command gets all the unresolved transactions in the default keyspace, which can be set by the use ks command.

Related Issue(s)

• RFC: Atomic Distributed Transactions #16245

Checklist

• "Backport to:" labels have been added if this change should be back-ported to release branches
• If this change is to be back-ported to previous releases, a justification is included in the PR description
• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on CI?
• Documentation was added or is not required

Deployment Notes

[harshit-gangal]

need to fix the existing engine test

[codecov]

Codecov Report

Attention: Patch coverage is 49.12281% with 29 lines in your changes missing coverage. Please review.

Please upload report for BASE (main@f2d5d1c). Learn more about missing BASE report.
Report is 3 commits behind head on main.

Files	Patch %	Lines
go/vt/vtgate/tx_conn.go	0.00%	12 Missing ⚠️
go/vt/vtgate/vcursor_impl.go	0.00%	10 Missing ⚠️
go/vt/sqlparser/ast_format.go	0.00%	5 Missing ⚠️
go/vt/vtgate/executor.go	0.00%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #16589   +/-   ##
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  Coverage        ?   68.82%           
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  Files           ?     1557           
  Lines           ?   199932           
  Branches        ?        0           
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  Hits            ?   137605           
  Misses          ?    62327           
  Partials        ?        0           

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