Evaluate if changes are needed for ServiceKeyLookupMode

[ericstj]

See https://github.com/dotnet/dotnet/pull/644/files#r2100901895

dotnet/runtime#114929 added support for ServiceKeyLookupMode since AspNetCore is reading this attribute and consuming the key value it may need to have different behavior for ServiceKeyLookupMode.InheritKey vs ServiceKeyLookupMode.NullKey. Let this issue track investigating that and adding any necessary tests.

[javiercn]

@ericstj I'm not supper familiar with this area, but let me see if my thinking is correct.

• This affects Get(Required)KeyedService calls within the framework.
• The behavior is about whether when resolving a Keyed service dependencies also use the same key during resolution.

Am I understanding this correctly?