feat: Remove MySQL and implement it all with Mongo

[withchao]

🔍 What type of PR is this?

👀 What this PR does / why we need it:

• My pull request adheres to the code style of this project
• My code requires changes to the documentation
• I have updated the documentation as required
• All the tests have passed

🅰 Which issue(s) this PR fixes:

Fixes #1507

📝 Special notes for your reviewer:

🎯 Describe how to verify it

📑 Additional documentation e.g., RFC, notion, Google docs, usage docs, etc.:

[codecov]

Codecov Report

Attention: 204 lines in your changes are missing coverage. Please review.

Comparison is base (4b19202) 4.86% compared to head (af951d8) 4.88%.

Files	Patch %	Lines
pkg/common/db/cache/group.go	0.00%	70 Missing ⚠️
pkg/common/convert/friend.go	0.00%	33 Missing ⚠️
internal/tools/msg.go	0.00%	31 Missing ⚠️
pkg/common/convert/user.go	40.00%	23 Missing and 1 partial ⚠️
pkg/common/db/cache/msg.go	0.00%	13 Missing ⚠️
pkg/common/db/cache/s3.go	0.00%	7 Missing ⚠️
internal/tools/conversation.go	0.00%	6 Missing ⚠️
internal/msggateway/n_ws_server.go	0.00%	5 Missing ⚠️
pkg/common/db/cache/meta_cache.go	0.00%	4 Missing ⚠️
pkg/common/db/cache/user.go	0.00%	4 Missing ⚠️
... and 5 more

Additional details and impacted files

@@           Coverage Diff            @@
##            main   #1508      +/-   ##
========================================
+ Coverage   4.86%   4.88%   +0.02%     
========================================
  Files         49      42       -7     
  Lines       4256    3787     -469     
========================================
- Hits         207     185      -22     
+ Misses      4037    3592     -445     
+ Partials      12      10       -2     

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