Link peer's X509 stack handle to parent SSL safe handle

[rzikm]

Fixes #109689.

Fixes rare data race between handshake and SslStream.Dispose() where we would try to access already freed STACKOF(X509) and crash.

I also reviewed other interop usages to make sure there are no similar bugs lurking elsewhere on SslStream codebase.

Tested locally by inserting artificial delays at relevant places.

PR Overview

This PR addresses a race condition during SSL/TLS handshakes by restructuring how the peer certificate chain is retrieved.

• Renames the original SslGetPeerCertChain method to a private implementation (SslGetPeerCertChain_private).
• Introduces a new public wrapper for SslGetPeerCertChain that uses SafeInteriorHandle.OpenInteriorHandle.

Reviewed Changes

File	Description
src/libraries/Common/src/Interop/Unix/System.Security.Cryptography.Native/Interop.Ssl.cs	Refactors peer certificate retrieval to link the parent SSL safe handle using a new wrapper method

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src/libraries/Common/src/Interop/Unix/System.Security.Cryptography.Native/Interop.Ssl.cs:126

• [nitpick] Consider renaming 'SslGetPeerCertChain_private' to a more conventional name such as 'SslGetPeerCertChainCore' to clarify its role as the internal implementation detail.

internal static partial SafeSharedX509StackHandle SslGetPeerCertChain_private(SafeSslHandle ssl);