[HLSL] emit-obj when set output.

When not set output, set default output to stdout.
When set output with -Fo and no -fcgl, set -emit-obj to generate dx container.

Reviewed By: beanz

Differential Revision: https://reviews.llvm.org/D130858

GitOrigin-RevId: 549542b494f4c84bead744ed91ea81236e4aaa63
4 files changed