Add analyzer for async delegates with LongRunning tasks

[SergeyTeplyakov]

Introduces EPC36, which warns when async delegates are used with Task.Factory.StartNew and TaskCreationOptions.LongRunning. Adds analyzer implementation, tests, documentation, and diagnostic descriptor. This helps prevent inefficient use of threads and clarifies intent when working with async code.

[Copilot]

Pull Request Overview

Adds a new analyzer (EPC36) that warns when async delegates are used with Task.Factory.StartNew combined with TaskCreationOptions.LongRunning, to prevent inefficient thread usage and clarify intent in async code.

• Introduces DiagnosticDescriptor EPC36 in DiagnosticDescriptors.cs.
• Implements analyzer logic in DoNotUseAsyncDelegatesForLongRunningTasksAnalyzer.cs, along with unit tests.
• Updates release notes and adds documentation for the new rule.

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/ErrorProne.NET.CoreAnalyzers/DiagnosticDescriptors.cs	Added EPC36 diagnostic descriptor for async delegates with LongRunning
src/ErrorProne.NET.CoreAnalyzers/AsyncAnalyzers/DoNotUseAsyncDelegatesForLongRunningTasksAnalyzer.cs	Implemented analyzer logic to detect async delegates in StartNew calls with LongRunning
src/ErrorProne.NET.CoreAnalyzers/AnalyzerReleases.Unshipped.md	Included EPC36 in the list of pending analyzer releases
src/ErrorProne.NET.CoreAnalyzers.Tests/AsyncAnalyzers/DoNotUseAsyncDelegatesForLongRunningTasksAnalyzerTests.cs	Added comprehensive tests covering correct and incorrect scenarios
docs/Rules/EPC36.md	Created documentation with examples and guidance for EPC36

Comments suppressed due to low confidence (1)

docs/Rules/EPC36.md:10

• The ordered list numbering jumps from 1 to 3. Renumber this item as '2.' to maintain correct sequence.

3. **Creating confusion**: The intent of the code becomes unclear - is it meant to be long-running synchronous work or efficient async work? Is it really the case that the synchronous block of the async method is taking a long time, or it's just a mistake?