* Add tests for basic `private protected` functionality.
* Constrain private protected to language version 7.2.
* Add tests for VB, and adjust existing VB tests as needed.
* Add test for SyntaxFacts production of source for private protected.
* Add VB tests corresponding to all C# tests for private protected
* Mention `private protected` in the compiler test plan.

* Compare lines instead of using AssertXml when validating PDBs.

AssertXml doesn't validate ordering.

* Reorder expected PDB XML nodes to match actual order

* Update to the latest Microsoft.DiaSymReader.* packages.

* Enable embedding sources to Windows PDBs

* Ref assemblies make a best effort to emit with determinism
* Fixing CopyRefAssembly message output
* CopyRefAssembly logs when input isn't ref assembly
* CopyRefAssembly does assembly redirect.
* Compact error codes for C# 7.1

* refonly and refout on command-line and msbuild
* corresponding change to Emit API
* Metadata-only assembly use `throw null` bodies
* Can no longer produce netmodule with metadata only

Fixes https://devdiv.visualstudio.com/DevDiv/_workitems?id=233669.

- VB: Report a warning about AssemblyKeyFile and AssemblyKeyName attributes being ignored by public signing.
- Disallow public signing for Net modules. The fact that the signing is public is not preserved in a module. The fact of signing is preserved by emitting attributes that are going to be ignored anyway if public signing is used.

Closes #11427.

Removing diagnostic IDs from previous versions of the VB compiler that are no longer generated by Roslyn.

Fixes #14895

This is the same fix as was implemented for C# in #13806, but for VB.

* tuples with names differing only by case are not allowed
* names that match predefined element names except for case do not result in additional names
* name-related errors are checked in case-insensitive fasion

* Implement source link feature

* Fix CommonCompiler to open source link stream, add E2E tests

* Reduce code duplication across VB and C#