[mlir][GPU] Extend GPU kernel outlining to generate DL specification

This patch extends the GPU kernel outlining pass so that it can take in
an optional data layout specification that will be attached to the GPU
module operation generated. If the data layout specification is not provided
the default data layout is used instead.

Reviewed By: herhut, mehdi_amini

Differential Revision: https://reviews.llvm.org/D115722