Share managed EventSource/EventPipe implementation between CoreCLR and Mono. (#33425)

Share managed EventSource/EventPipe implementation between CoreCLR and Mono. (#33425)

First changes needed in order to start sharing managed EventSource/EventPipe
code between CoreCLR and Mono runtime. Sharable code has been moved into
S.P.C library project and split into runtime specific source files when
needed, kept within each runtime specific S.P.C project files.

Mono runtime has been extended with a set of icalls needed by
EventPipeInternal, just to make sure EventPipe can be initialized,
current Mono runtime implementation returns dummy values.

Current change also enables ETW provider support on Mono Windows runtime.

NOTE, this is just initial changes needed in order to share managed
EventSource/EventPipe code between runtimes. Future changes will incrementally
add EventPipe native code into Mono runtime.