[mlir][spirv] Serialize all operands together if possible

SPIR-V ops can mix operands and attributes in the definition. These
operands and attributes are serialized in the exact order of the definition
to match SPIR-V binary format requirements. It can cause excessive
generated code bloat because we are emitting code to handle each
operand/attribute separately. So here we probe first to check whether all
the operands are ahead of attributes. Then we can serialize all operands
together.

This removes ~1000 lines of code from the generated inc file.

Differential Revision: https://reviews.llvm.org/D79446