feat: Add Problem Matcher for dotnet-format

[nogic1008]

Description:
Add Problem Matcher for dotnet format command.

• Working sample
  

Related issue:
No

Check list:

• Mark if documentation changes are required.
• Mark if tests were added or updated to cover the changes.

[nogic1008]

I overlooked unit tests for csc.json. I'll rewrite it.

[Copilot]

Pull Request Overview

This PR adds a problem matcher for the dotnet format command to enable automatic annotation of formatting issues in GitHub Actions workflows.

Key changes:

• Refactored problem matcher registration to support multiple matchers via an array
• Added dotnet-format.json problem matcher configuration file
• Consolidated test files for problem matchers into a unified test suite

Reviewed Changes

Copilot reviewed 5 out of 6 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/setup-dotnet.ts	Refactored to register multiple problem matchers from an array instead of hardcoding a single matcher path
dist/setup/index.js	Compiled/bundled version of the source changes
.github/dotnet-format.json	New problem matcher configuration for dotnet format output parsing
__tests__/setup-dotnet.test.ts	Added test assertions to verify both problem matchers are registered
__tests__/problem-matchers.json.test.ts	New unified test file for validating both csc and dotnet-format problem matcher patterns
__tests__/csc.test.ts	Removed old standalone test file (tests moved to new consolidated file)

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[Copilot]

The regex pattern for capturing the 'code' field (capture group 5) uses .+ which is too greedy. Based on the test case, the code should match WHITESPACE but the pattern will incorrectly capture everything up to the last colon before the message. Consider using ([A-Z_]+) or ([^:]+) to match the diagnostic code more precisely.

Suggested change

	"regexp": "^\\s*(.*)\\((\\d+),(\\d+)\\):\\s+(error|warning)\\s+(.+):\\s+(.*)\\s+\\[(.+)\\]$",
	"regexp": "^\\s*(.*)\\((\\d+),(\\d+)\\):\\s+(error|warning)\\s+([^:]+):\\s+(.*)\\s+\\[(.+)\\]$",

[Copilot]

The test uses for...in loop without checking hasOwnProperty, which could iterate over inherited properties. Consider using Object.keys(expected).forEach(key => ...) or add a hasOwnProperty check for safer iteration.

[Copilot]

The test uses for...in loop without checking hasOwnProperty, which could iterate over inherited properties. Consider using Object.keys(expected).forEach(key => ...) or add a hasOwnProperty check for safer iteration.