Limit polyfill to only lock type

[viceroypenguin]

No description provided.

[Copilot]

Pull request overview

Adds an explicit configuration in the shared MSBuild props to restrict Meziantou.Polyfill usage to only the System.Threading.Lock polyfill across the solution.

Changes:

• Introduces an “Enabled Polyfills” property group in Directory.Build.props.
• Sets MeziantouPolyfill_IncludedPolyfills to target T:System.Threading.Lock.

[Copilot]

<Polyfill></Polyfill> followed by <Polyfill>$(Polyfill)|T:System.Threading.Lock</Polyfill> expands to a value that starts with a leading | (because $(Polyfill) is empty). If MeziantouPolyfill_IncludedPolyfills doesn’t tolerate empty entries, this can prevent the Lock polyfill from being applied (and break net8 builds). Prefer setting MeziantouPolyfill_IncludedPolyfills directly to T:System.Threading.Lock, or append conditionally only when the existing value is non-empty (and avoid the extra Polyfill property altogether).

Suggested change

	<Polyfill></Polyfill>
	<Polyfill>$(Polyfill)|T:System.Threading.Lock</Polyfill>
	<MeziantouPolyfill_IncludedPolyfills>$(Polyfill)</MeziantouPolyfill_IncludedPolyfills>
	</PropertyGroup>
	<PropertyGroup Condition="'$(GITHUB_ACTIONS)' == 'true'">
	<MeziantouPolyfill_IncludedPolyfills>T:System.Threading.Lock</MeziantouPolyfill_IncludedPolyfills>
	</PropertyGroup>
	<PropertyGroup Condition="'$(GITHUB_ACTIONS)' == 'true'">
	<PropertyGroup Condition="'$(GITHUB_ACTIONS)' == 'true'">

[Copilot]

XML comment formatting: add a space after <!-- for readability/consistency (e.g., <!-- https://... -->).

Suggested change

	<!--https://github.com/meziantou/Meziantou.Polyfill?tab=readme-ov-file#supported-polyfills-->
	<!-- https://github.com/meziantou/Meziantou.Polyfill?tab=readme-ov-file#supported-polyfills-->