feat: implement the drop database parser

[WenyXu]

I hereby agree to the terms of the GreptimeDB CLA.

Refer to a related PR or issue link (optional)

• Tracking issue for drop database  #3516
• Supports drop schema/database statement #825

What's changed and what's your intention?

Implement the drop database parser

Checklist

• I have written the necessary rustdoc comments.
• I have added the necessary unit tests and integration tests.
• This PR does not require documentation updates.

[codecov]

Codecov Report

Attention: Patch coverage is 83.33333% with 17 lines in your changes are missing coverage. Please review.

Project coverage is 84.96%. Comparing base (5ad3b79) to head (450bf85).
Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3521      +/-   ##
==========================================
- Coverage   85.31%   84.96%   -0.35%     
==========================================
  Files         904      905       +1     
  Lines      150248   150828     +580     
==========================================
- Hits       128178   128147      -31     
- Misses      22070    22681     +611