ILVerify: split into exe and library

[jcouv]

Per discussion in #5235, the library code and corresponding tests go into src/ILVerification, while the command-line exe is produced from src/ILVerify.

I kept a single solution (under ILVerify) which points to the three projects.

Aside from solution and project file changes, the code changes were:

• Program.cs was removed from ILVerification and moved to ILVerify.
• The resource file for ILVerification changed name.
• Added some InternalsVisibleTo to ILVerify.

Fixes #5235
Relates to dotnet/roslyn#22872

Tagging @jkotas @ArztSamuel @A-And

[jcouv]

Hum, it looks like I need to work on the command-line build, as CI produced:
D:\j\workspace\release_windo---c2468dc6\dir.traversal.targets(24,5): error : (No message specified) [D:\j\workspace\release_windo---c2468dc6\src\dirs.proj]

[ArztSamuel]

LGTM!

Out of personal interest: Do you think it would be a desirable goal to change the code at some point, to only rely on the public interface without having to expose internals to both ILVerify and the Tests projects?

[jkotas]

Do you think it would be a desirable goal to change the code at some point, to only rely on the public interface without having to expose internals to both ILVerify and the Tests projects?

Yes, it would be definitely a desirable goal.

[jkotas]

Nit: It would be nice to use relative URLs for the relative tree links so that the links stay valid when the repo is forked or branched.