refactor: separate the quote char and value

[WenyXu]

I hereby agree to the terms of the GreptimeDB CLA.

Refer to a related PR or issue link (optional)

#3174

What's changed and what's your intention?

Separating the quote char and value allows us to cover more cases easily.

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 59.52381% with 51 lines in your changes are missing coverage. Please review.

Project coverage is 85.02%. Comparing base (a218f12) to head (377c143).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3455      +/-   ##
==========================================
- Coverage   85.42%   85.02%   -0.41%     
==========================================
  Files         896      896              
  Lines      147137   147185      +48     
==========================================
- Hits       125696   125139     -557     
- Misses      21441    22046     +605     

[fengjiachun]

LGTM