Replace Altinn3.ruleset with .editorconfig

[SandGrainOne]

Description

Replacing the deprecated Altinn3.ruleset file with a new .editorconfig file.

• Created a .editorconfig file with the rules from Altinn3.ruleset file.
• Deleted the Altinn3.ruleset file and removed project references
• Fixed all Analyzer errors/warnings

Verification

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

[sonarcloud[bot]]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

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0.0% Duplication