fix: canonicalize catalog and schema names

[killme2008]

I hereby agree to the terms of the GreptimeDB CLA.

Refer to a related PR or issue link (optional)

What's changed and what's your intention?

Before this patch, the following SQL will fail:

USE INFORMATION_SCHEMA;

Unknown database 'INFORMATION_SCHEMA'.

We must always treat the catalog and schema in lowercase.

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 80.43478% with 9 lines in your changes are missing coverage. Please review.

Project coverage is 84.96%. Comparing base (92a8e86) to head (a703f9d).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3600      +/-   ##
==========================================
- Coverage   85.35%   84.96%   -0.39%     
==========================================
  Files         931      931              
  Lines      154611   154618       +7     
==========================================
- Hits       131961   131366     -595     
- Misses      22650    23252     +602     

[shuiyisong]

LGTM

[tisonkun]

LGTM