feat: date & timestamp type

[aceforeverd]

1. support date & timestamp type
   you can use time.Time to represent SQL timestamp type, and openmldb.NullDate to represent date type
2. simply mode in DSN
   only online & offline, and later option request, rm offsync or offasync
3. deps: upgrade testify to v1.9.0

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 55.93220% with 26 lines in your changes are missing coverage. Please review.

Project coverage is 57.75%. Comparing base (c046517) to head (ec47d14).

Files	Patch %	Lines
conn.go	62.06%	9 Missing and 2 partials ⚠️
types.go	50.00%	8 Missing and 2 partials ⚠️
driver.go	50.00%	4 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main       #7      +/-   ##
==========================================
- Coverage   57.86%   57.75%   -0.11%     
==========================================
  Files           2        3       +1     
  Lines         159      187      +28     
==========================================
+ Hits           92      108      +16     
- Misses         51       61      +10     
- Partials       16       18       +2     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.