Add Roslyn Analyzer NoWarn support + Other improvements

[mfogliatto]

Description

Adds Roslyn Analyzer NoWarn support by collecting project NoWarn entries and applying them in the analyzer.

Additonally, adds a ToString() override on ReferenceEvaluationContext to improve diagnostics and test assertions and fixes the Copilot instructions file location.

This PR is a follow-up to the pending Roslyn Analyzer support referenced in issue #23.

Type of change

• Enhancement (e.g. new feature, functional improvement, etc.)
• Bug fix
• Chore (e.g. refactoring, documentation, etc.)

Related Issue

Follow-up to #23 — Roslyn Analyzer support (missing NoWarn handling)

How Has This Been Tested?

• Unit test updated/fixed in this branch.
• Uptaking package in the local feed for validation with a test project.

Screenshots (if applicable)

Not applicable.

Additional context

Commits included in this PR (most recent first):

• a7a8049 — Add NoWarn collection for Roslyn Analyzer NoWarn support (Marco Fogliatto, Sat Aug 23 08:06:04 2025 +0200)
• 4d906a4 — Add ToString for ReferenceEvaluationContext (Marco Fogliatto, Sat Aug 23 07:59:33 2025 +0200)
• 83360b3 — Fix Copilot instructions file location (Marco Fogliatto, Sat Aug 23 07:16:44 2025 +0200)
• 5f23466 — Fix unit test (Marco Fogliatto, Sat Aug 9 12:39:12 2025 +0200)

Notes:

• Primary change: Roslyn analyzer now recognizes project NoWarn entries so analyzer diagnostics can be suppressed via standard NoWarn configuration.
• Added ToString() to ReferenceEvaluationContext to make debugging and assertions more convenient.