[MAT-482] Adds the checker options to QR related routines.

This adds the template based input checker to templated routines
xgeqrf() and xxxgqr(). It also updates the unit tests of said
routines with respect to this change.
[MAT-482] Add QR node and impl.

This adds the outline implementation of the QR functionality
and a set of unit tests. It probably needs more work to be
efficient and to allow for options like "thin" QR as per
Golub and Van Loan.