spirv-opt, consider adding (for SPIR-V 1.1 and later) OpModuleProcessed

Consumers of SPIRV would benefit in seeing that a SPIRV module had been processed by spirv-opt. For example if a consumer detected that spirv-opt had not been run then it could invoke the tool prior to it's own processing. Conversely, a run of spirv-opt could be omitted if it was found to already be run.

(One could run spirv-opt iteratively and add optimizations that were perhaps omitted in earlier runs.)

I would proposed adding (minimally) a string that included the tool name, tool version and options passed in.

Start by researching SPIR-V 1.1's OpModuleProcessed instruction and how spirv-opt represents tool metadata. Define the required tool name, version, and options semantics, including repeated optimization runs; the issue does not identify implementation files or tests, so those would need to be located before work begins.

Written by the indexing model from the issue text.