Add JSON data type

[congqixia]

See also #432
Related to milvus-io/milvus#23389
/kind enhancement

[sre-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: congqixia

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [congqixia]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[codecov]

Codecov Report

Merging #443 (5665f9f) into master (e6dc380) will increase coverage by 0.13%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #443      +/-   ##
==========================================
+ Coverage   87.35%   87.48%   +0.13%     
==========================================
  Files          31       32       +1     
  Lines        2878     2909      +31     
==========================================
+ Hits         2514     2545      +31     
  Misses        274      274              
  Partials       90       90              

Impacted Files	Coverage Δ
entity/columns_json.go	100.00% <100.00%> (ø)
entity/schema.go	93.44% <100.00%> (+0.33%)	⬆️

[yah01]

/lgtm