Add a util function to generate the relative redirectUrl

[SuZhou-Joe]

Description

This PR adds a new util function to src/core/server/http/http_tools.ts, and the util function should be used by security plugin or other customized authentication plugin to generate the correct redirect url after login.

Issues Resolved

partial closes: opensearch-project/security-dashboards-plugin#2069

Screenshot

Only serve side code changes involved.

Testing the changes

The consumer logic is inside opensearch-project/security-dashboards-plugin#2072

Changelog

• feat: Add a util function to generate the relative redirectUrl.

Check List

• All tests pass
  • yarn test:jest
  • yarn test:jest_integration
• New functionality includes testing.
• New functionality has been documented.
• Update CHANGELOG.md
• Commits are signed per the DCO using --signoff

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 63.64%. Comparing base (61d5c49) to head (9ee89ee).
Report is 229 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #7600   +/-   ##
=======================================
  Coverage   63.64%   63.64%           
=======================================
  Files        3634     3634           
  Lines       80099    80104    +5     
  Branches    12682    12683    +1     
=======================================
+ Hits        50977    50984    +7     
+ Misses      26015    26014    -1     
+ Partials     3107     3106    -1     

Flag	Coverage Δ
Linux_1	30.56% <0.00%> (-0.01%)	⬇️
Linux_2	55.59% <100.00%> (+<0.01%)	⬆️
Linux_3	40.58% <0.00%> (-0.01%)	⬇️
Linux_4	31.32% <0.00%> (-0.01%)	⬇️
Windows_1	30.57% <0.00%> (-0.01%)	⬇️
Windows_2	55.54% <100.00%> (+<0.01%)	⬆️
Windows_3	40.58% <0.00%> (-0.01%)	⬇️
Windows_4	31.32% <0.00%> (-0.01%)	⬇️

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