feat: add apis to handle bookmark tags

[fmartingr]

• Added new APIs to handle bookmark-tags associations
• Added a way to search for tags in GET /api/v1/tags/?search=...
• 🚨 Breaking change: The API output now does not have a {"message":...} root key by default. API outputs are the same as exposed in the API documentation.
• Experimental: new incomplete experimental web app toggable with the SHIORI_HTTP_SERVE_WEB_UI_V2 environment variable.

#658

[codecov]

Codecov Report

Attention: Patch coverage is 72.62693% with 124 lines in your changes missing coverage. Please review.

Project coverage is 49.68%. Comparing base (21165aa) to head (69a4422).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
internal/testutil/response.go	0.00%	43 Missing ⚠️
internal/http/handlers/api/v1/bookmarks.go	82.30%	16 Missing and 4 partials ⚠️
internal/domains/bookmarks.go	66.66%	8 Missing and 4 partials ⚠️
internal/http/middleware/cors.go	0.00%	12 Missing ⚠️
internal/database/database_tags.go	89.52%	9 Missing and 2 partials ⚠️
internal/http/handlers/frontend.go	53.84%	4 Missing and 2 partials ⚠️
internal/cmd/server.go	0.00%	5 Missing ⚠️
internal/http/templates/templates.go	58.33%	4 Missing and 1 partial ⚠️
internal/config/config.go	0.00%	3 Missing and 1 partial ⚠️
internal/http/handlers/api/v1/accounts.go	78.57%	3 Missing ⚠️
... and 3 more

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1081      +/-   ##
==========================================
+ Coverage   48.52%   49.68%   +1.16%     
==========================================
  Files          72       73       +1     
  Lines        7001     7320     +319     
==========================================
+ Hits         3397     3637     +240     
- Misses       3299     3366      +67     
- Partials      305      317      +12     

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