This was a LOT harder to review than it should have been. Too many types of changes in a single commit.

These are the only (non-comment) lines that were added, as best as I can tell:

dotnet_style_prefer_simplified_boolean_expressions = true:warning
csharp_style_prefer_switch_expression = true:warning
csharp_style_prefer_pattern_matching = true:warning
csharp_style_prefer_not_pattern = true:warning
csharp_style_implicit_object_creation_when_type_is_apparent = true:warning
dotnet_remove_unnecessary_suppression_exclusions = none:warning

Would have been better to have distinct commits for the three types of changes:

1. Removal or update of dead links
2. Moving (unchanged) lines
3. Adding new settings

Reviewed so that others can more easily see the effective differences.