Implement 'ConditionalWeakTable<TKey,TValue>.GetOrAdd' APIs

[Sergio0694]

Closes #89002

This PR implements the new APIs for ConditionalWeakTable<TKey, TValue> and hides some legacy ones:

namespace System.Runtime.CompilerServices;

public sealed partial class ConditionalWeakTable<TKey, TValue>
{
+   public TValue GetOrAdd(TKey key, TValue value);
+   public TValue GetOrAdd(TKey key, Func<TKey, TValue> valueFactory);
+   public TValue GetOrAdd<TArg>(TKey key, Func<TKey, TArg, TValue> valueFactory, TArg factoryArgument)
+       where TArg : allows ref struct;
    
+   [EditorBrowsable(EditorBrowsableState.Never)]
    public TValue GetValue(TKey key, CreateValueCallback createValueCallback);
  
+   [EditorBrowsable(EditorBrowsableState.Never)]
    public TValue GetOrCreateValue(TKey key);

+   [EditorBrowsable(EditorBrowsableState.Never)]
    public delegate TValue CreateValueCallback(TKey key);
}

[dotnet-issue-labeler]

Note regarding the new-api-needs-documentation label:

This serves as a reminder for when your PR is modifying a ref *.cs file and adding/modifying public APIs, please make sure the API implementation in the src *.cs file is documented with triple slash comments, so the PR reviewers can sign off that change.

[dotnet-issue-labeler]

Note regarding the new-api-needs-documentation label:

This serves as a reminder for when your PR is modifying a ref *.cs file and adding/modifying public APIs, please make sure the API implementation in the src *.cs file is documented with triple slash comments, so the PR reviewers can sign off that change.

[Copilot]

Copilot reviewed 2 out of 3 changed files in this pull request and generated 1 comment.

Files not reviewed (1)

• src/libraries/System.Runtime/ref/System.Runtime.cs: Evaluated as low risk

[jkotas]

Go over Corelib and maybe other core assemblies and switch them to use the new API where appropriate? There are not that many candidates.

[Sergio0694]

I've gone over uses I could find of the now hidden methods and replaced them. Particularly happy with how ComWrappers on Native AOT looks now, it could drop a couple of extra lookups entirely. @jkoritzinsky can you help take a look? 🙂