feat: impl instant query interface

[waynexia]

I hereby agree to the terms of the GreptimeDB CLA

What's changed and what's your intention?

Implement the query API of Prometheus server. It's used to perform instant query

Checklist

• I have written the necessary rustdoc comments.
• I have added the necessary unit tests and integration tests.

Refer to a related PR or issue link (optional)

[codecov]

Codecov Report

Merging #1410 (d4d9b83) into develop (408de51) will decrease coverage by 0.57%.
The diff coverage is 83.09%.

@@             Coverage Diff             @@
##           develop    #1410      +/-   ##
===========================================
- Coverage    86.00%   85.44%   -0.57%     
===========================================
  Files          533      534       +1     
  Lines        79474    79602     +128     
===========================================
- Hits         68350    68012     -338     
- Misses       11124    11590     +466     

[yuanbohan]

what's the behavior if the table is not exist? Prometheus prefers empty result instead of TableNotExistError, and it does make sense in Prometheus compatible services, like AlertManager, Grafana, etc,.

[waynexia]

what's the behavior if the table is not exist? Prometheus prefers empty result instead of TableNotExistError, and it does make sense in Prometheus compatible services, like AlertManager, Grafana, etc,.

Makes sense to return an empty result in this API. I'll add a hook after query execution to convert this kind of error

[waynexia]

Just found it's already done when I implemented query_range lol. PTAL again @yuanbohan