Remove mentions of Rotor from codebase (#20298)

Remove mentions of Rotor from codebase (#20298)

* Moving parsing from TypeNameParser ctor to a separate method.

It seems a bit odd to have the constructor parsing and then use
a dummy method (MakeRotorHappy) to make it look more normal.

* Remove CorMarkThreadInThreadPool.

It is neither referenced nor exported.

* Remove reference to rotor from securitywrapper.h

* Remove reference to rotor from Strike/vm.cpp.

This file is only built for Windows.

* Remove reference to rotor from debugreturn.h

This is the only file the defines these macros, so there is no need to
undef them first.

* Remove unused code refering to rotor from PAL.

* Remove references to Rotor from PAL.

* Remove references to deleted tests from DisabledTests.txt

I can't find any evidence that this file is actually used.

* Remove unneeded casts.

* Remove dead and misleading code from profilinghelper.cpp.

FEATURE_PROFAPI_EVENT_LOGGING is always defined when PROFILING_SUPPORTED
is defined. And the entire contents of profilinghelper.cpp is surrounded
with "ifdef PROFILING_SUPPORTED". So all sections in
"ifndef FEATURE_PROFAPI_EVENT_LOGGING" are dead.

Furthermore, in coreclr this does not use the eventlog, so the macro name
is misleading.

* Remove dead code in excep.cpp.

This entire function is surrounded with "ifndef FEATURE_PAL".

* Remove refererences to rotor from safemath.h

This does not appear to cause any compile problems, so nobody was using
safemath.h without _ASSERTE defined.

Also S_SIZE_T_WP64BUG is not used anywhere.

* Remove dead code from palclr.h.

I don't know why these check to see if the macro is undefined immediately
after defining them.

Also the comment appears to reference some unions that are no longer in
this file.

* Expose ISymUnmanagedWriter2 from SymWriter as required by COM.

The comment talks about the C# compiler using this, however I cannot see
a way for the C# compiler to get an instance of this. It is only used
internally by AssemblyBuilder and not exposed otherwise.

* Restore check for _ASSERTE in safemath.h.

On Windows sometimes that this file is included without
_ASSERTE being defined. As the existing comment suggests, it appears
that SOS explicitly does not want _ASSERTE to do anything.