Re-land "[lldb/CMake] Auto-generate the Initialize and Terminate calls for plugin"

This patch changes the way we initialize and terminate the plugins in
the system initializer. It uses an approach similar to LLVM's
TARGETS_TO_BUILD with a def file that enumerates the plugins.

Previous attempts to land this failed on the Windows bot because there's
a dependency between the different process plugins. Apparently
ProcessWindowsCommon needs to be initialized after all other process
plugins but before ProcessGDBRemote.

Differential revision: https://reviews.llvm.org/D73067