Move methods from Command to AbstractPDOCommand

[Tigrov]

Related with yiisoft/db#770

Q	A
Is bugfix?	❌
New feature?	❌
Breaks BC?	❌
Fixed issues	-

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (997ae8b) 98.53% compared to head (61e446c) 98.48%.

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #283      +/-   ##
============================================
- Coverage     98.53%   98.48%   -0.05%     
+ Complexity      215      205      -10     
============================================
  Files            15       15              
  Lines           615      596      -19     
============================================
- Hits            606      587      -19     
  Misses            9        9              

Files	Coverage Δ
src/Command.php	100.00% <ø> (ø)

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[what-the-diff]

PR Summary

• Removed Unused Elements in Command.php
  Throughout the file Command.php, various aspects that were no longer needed were removed. These include imports and sections of commented out code that are not being used for anything.

• Deleted Redundant Methods
  This pull request also includes the removal of the unused methods internalExecute and getQueryBuilder. These methods were found to be redundant and not serving a key function.

• Eliminated Unused Exceptions
  A cleanup of the use statement in Command.php has been done with the removal of unused exceptions and throwable.

• Unused Variable Removed
  A variable named $rawSql that was present in the internalExecute method but unused, has been removed ensuring cleaner and more efficient code.

• Removed Redundant Method
  The redundant showDatabases method within Command.php was also removed to streamline the code and improve readability.