Remove .NET Framework remarks (System.IO)

[gewarren]

.NET Framework API ref has moved to its own repo (https://github.com/dotnet/dotnetfw-api-docs), so we can clean up .NET Framework remarks, exceptions, and code examples out of this repo. Contributes to #12513.

Removes remarks and examples related to:

• .NET Framework versions
• Code-access security
• Configuring apps via app.config file
• App domains

Also remarks all remarks from obsolete APIs.

Hide whitespace changes

[dotnet-policy-service]

Tagging subscribers to this area: @dotnet/area-system-io

[Copilot]

Pull request overview

This PR cleans up the .NET API reference docs by removing or rewriting .NET Framework-specific remarks, exceptions, and examples across System.IO and related namespaces, aligning the content with the post-split documentation layout.

Changes:

• Removes/rewrites remarks that referenced .NET Framework versions, app domains, CAS, and Windows Store app-specific guidance.
• Simplifies and modernizes async/I/O guidance in stream-related types and compression streams.
• Updates related links and exception descriptions to avoid framework-specific qualifiers.

Reviewed changes

Copilot reviewed 21 out of 21 changed files in this pull request and generated 12 comments.

Show a summary per file

File	Description
xml/System.IO/Stream.xml	Updates async and Windows Runtime stream conversion remarks to remove .NET Framework-specific phrasing.
xml/System.IO/PathTooLongException.xml	Removes .NET Framework version gating from long-paths remarks.
xml/System.IO/Path.xml	Removes framework/version-specific path-validation notes and adjusts device-path wording.
xml/System.IO/InternalBufferOverflowException.xml	Rewords remarks to remove “.NET Framework” references in constructor guidance.
xml/System.IO/FileSystemInfo.xml	Simplifies exception descriptions to avoid framework-specific qualifiers.
xml/System.IO/FileSystemAclExtensions.xml	Updates remarks describing why these extension methods exist, removing “.NET Core” phrasing.
xml/System.IO/FileStream.xml	Removes framework/version-specific exception notes and streamlines async remarks.
xml/System.IO/FileInfo.xml	Removes framework/version-specific exception notes.
xml/System.IO/FileAttributes.xml	Removes “.NET Core” qualification from platform-support notes.
xml/System.IO/File.xml	Removes framework/version-specific exception notes and .NET Core-specific guidance in Encrypt/Decrypt remarks.
xml/System.IO/DirectoryInfo.xml	Updates Parent remarks to remove cross-framework behavioral notes.
xml/System.IO/Directory.xml	Removes framework/version-specific exception notes and updates Move behavior note.
xml/System.IO/BufferedStream.xml	Removes .NET Framework version notes from async legacy APIs and streamlines remarks.
xml/System.IO.Pipes/PipeStream.xml	Removes “.NET Framework” phrasing from the type-level remarks.
xml/System.IO.Packaging/PackageDigitalSignatureManager.xml	Removes “.NET Framework” phrasing from type-level remarks.
xml/System.IO.Packaging/Package.xml	Removes “.NET Framework” phrasing from type-level remarks.
xml/System.IO.MemoryMappedFiles/MemoryMappedFile.xml	Removes “.NET Core and .NET 5+ only” qualifiers from PNSE exception docs.
xml/System.IO.IsolatedStorage/IsolatedStorageFile.xml	Removes .NET Framework-specific remarks and adjusts property docs.
xml/System.IO.Compression/GZipStream.xml	Simplifies zlib/async legacy remarks to remove .NET Framework references.
xml/System.IO.Compression/DeflateStream.xml	Simplifies zlib/async legacy remarks and removes .NET Framework references.
xml/System.IO.Compression/BrotliStream.xml	Updates async remarks to remove Windows Store app phrasing.