Don't expose TrustedCertificatesDirectory() and StartNewTlsSessionContext() to NetFx

[steveharter]

Fixes #113947

Will need to backport to v9 and v8.

[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]

Pull Request Overview

This PR prevents exposing the TrustedCertificatesDirectory property and StartNewTlsSessionContext method to NetFx by conditionally compiling them for NET targets only.

• Guard TrustedCertificatesDirectory with #if NET and mark it with the UnsupportedOSPlatformAttribute.
• Guard StartNewTlsSessionContext with #if NET and mark it accordingly.

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[teo-tsirpanis]

That's a breaking change, isn't it?

[steveharter]

That's a breaking change, isn't it?

No. The method was just introduced and is not implemented on .NET Framework.