Vector Variable Output for Mesh Function

[csdechant]

This PR adds additions and tests for MeshFunction::operator() that allows for Lagrange, Nedelec, and Raviart Thomas vector variables.

[moosebuild]

Job Test MOOSE clang on b2cfed7 : invalidated by @roystgnr

problems/eigen_problem/arraykernels.eigen/two_variables_precond_include_eigen_kernels CSVDiff, only with threads? Got to be a bug downstream, not this PR.

[moosebuild]

Job Coverage, step Generate coverage on f3d95aa wanted to post the following:

Coverage

	5868ff	#4165 f3d95a
	Total	Total	+/-	New
Rate	64.28%	64.31%	+0.03%	93.48%
Hits	75108	75168	+60	43
Misses	41736	41712	-24	3

Diff coverage report

Full coverage report

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