Add generate crash dump command to diagnostics server (#24460)

Add generate crash dump command to diagnostics server (#24460)

Add the DiagnosticProtocolHelper class to deserialize and dispatch
the new GenerateCoreDump command.

Refactor the PAL createdump launch on unhandled exception code to
used by a new PAL_GenerateCoreDump method that doesn't depend on
the complus dump environment variables.

Changed the "full" createdump not to include the uncommitted pages and
removed the "add module metadata" workaround for SOS clrstack !UNKNOWN
problem now that is fixed in SOS (crashinfo.cpp).