[RFC] UnitTestFrameworkPkg cmocka submodule alternatives

["Michael D Kinney" <michael.d.kinney@intel.com>]

Hello,

We have had at least three incidents in the last year where the link to the
cmocka submodule in the UnitTestFrameworkPkg has not been available, and this
impacted the EDK II CI system.  The following submodule link is the one that
is not reliable:

	https://git.cryptomilk.org/projects/cmocka.git

We have identified two potential mirrors of this repo:

	https://github.com/neverware-mirrors/cmocka.git
	https://gitlab.com/cmocka/cmocka.git

The following patch provided a temporary fix for the EDK II CI agents, but
does not help other consumers of the edk2 repository.

	https://github.com/tianocore/edk2/commit/be746104d1766a8c363e74d6063144657820d688

I have seen one suggestion that TianoCore create its own
mirror of cmocka.  This does require monitoring and maintenance
by the  TianoCore community.  I would prefer to use a well
maintained mirror in github as long as we do not observe any
issues with the support of that mirror.

I propose we update the submodule in the UnitTestFrameworkPkg
to use the https://github.com/neverware-mirrors/cmocka.git mirror.
By using a mirror in github, we remove one external dependency.

Please provide feedback and comments on this proposal.  If there
are no objections, then we will proceed with a patch review for
this update.

Thanks,

Mike