Add optional ToString() interceptor

[andrewlock]

• Adds an optional interceptor for the ToString() method.
• Bumps the Roslyn API to 4.11.0 as uses the new interceptor API.
  • Requires the 8.0.4xx+ SDK
• Adds a helper for passing analyzer config to tests
• Allow optionally enabling/disabling interceptors

[github-actions]

Test Results

   127 files  + 38     127 suites  +38   3m 42s ⏱️ +21s
 3 909 tests +  8   3 909 ✅ +  8  0 💤 ±0  0 ❌ ±0 
72 774 runs  +116  72 774 ✅ +116  0 💤 ±0  0 ❌ ±0 

Results for commit 89ed3c9. ± Comparison against base commit 987dfcb.

♻️ This comment has been updated with latest results.