feat: redis cache

[mirkoSekulic]

Description

Adds rediscache backplane for SignalR server.
Replaces Postgresql DistributedCache with Redis.

Related Issue(s)

• Prevent SignalR to switch connection when Designer is scaled to multiple replicas #14074

Verification

• Your code builds clean without any errors or warnings
• Manual testing done (required)
• Relevant automated test added (if you find this hard, leave it and we'll help out)

Documentation

• User documentation is updated with a separate linked PR in altinn-studio-docs. (if applicable)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.33%. Comparing base (ab1a970) to head (ae8feae).
Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #14158   +/-   ##
=======================================
  Coverage   95.33%   95.33%           
=======================================
  Files        1783     1783           
  Lines       23230    23230           
  Branches     2693     2693           
=======================================
  Hits        22147    22147           
  Misses        836      836           
  Partials      247      247           

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