Change FunctionNotFound analyzer severity to Info for cross-assembly scenarios

[Copilot]

DURABLE2003/DURABLE2004 analyzers report false positives when activity functions or sub-orchestrations are defined in referenced assemblies, since Roslyn analyzers cannot resolve symbols across assembly boundaries at compile time.

Changes

• Severity: Changed from Warning to Info for both DURABLE2003 (activity) and DURABLE2004 (sub-orchestration)
• Diagnostic message: Added clarification that cross-assembly functions can be safely ignored:

  "If the function is defined in another assembly, this diagnostic can be safely ignored. Static resolution across referenced assemblies is not supported."

• Documentation: Updated AnalyzerReleases.Shipped.md to reflect severity change

Example diagnostic output

Before:

warning DURABLE2003: The activity function 'SayHello' was not found in the current compilation. Ensure the activity is defined and the name matches exactly.

After:

info DURABLE2003: The activity function 'SayHello' was not found in the current compilation. Ensure the activity is defined and the name matches exactly. If the function is defined in another assembly, this diagnostic can be safely ignored. Static resolution across referenced assemblies is not supported.

Original prompt

make changes to make functionnotfound analyzers severity level to info, also the diagnostic message should indicate something like
If the function is defined in another assembly, this diagnostic can be safely ignored.
Static resolution across referenced assemblies is not supported. #580

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[Copilot]

Pull request overview

This PR addresses false positives in the FunctionNotFoundAnalyzer (DURABLE2003/DURABLE2004) by downgrading their severity from Warning to Info and clarifying that cross-assembly function references cannot be validated at compile time.

Key Changes:

• Severity changed from DiagnosticSeverity.Warning to DiagnosticSeverity.Info for both DURABLE2003 and DURABLE2004
• Diagnostic messages updated to clarify that cross-assembly functions are not statically resolvable
• Documentation updated to use "Reports" instead of "Warns" to reflect the Info severity level

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
src/Analyzers/Activities/FunctionNotFoundAnalyzer.cs	Updated severity from Warning to Info for both ActivityNotFoundRule and SubOrchestrationNotFoundRule
src/Analyzers/Resources.resx	Added clarification text to diagnostic messages explaining that cross-assembly functions can be safely ignored
src/Analyzers/AnalyzerReleases.Shipped.md	Updated documentation to reflect Info severity and changed "Warns" to "Reports" with added cross-assembly explanation