clean #90 backport

[mofeing]

i wasn't aware of #90 but there are things that shouldn't have been merged. there are a couple of differences with the Reactant copy of MLIR.jl:

1. mlirOperationInject (used by tryinject!) is implemented only in libReactantExtra, so any other build of libMLIR will error because it won't find the symbol. also, it was more an useful experiment at the time, that seen in perspective now, it wasn't maybe a great idea and we should probably remove it.
2. Random and StableRNGs are just used for adding a lil hash we suffix to the filenames of the MLIR dumps. in the context of Reactant, it may make sense because we already use those libs for other stuff, but it's an overkill here. also, i personally find that hash really annoying when dumping MLIR to files because filenames are already suffixed with a counter and can't understand why we need that random suffix.

cc @simeonschaub

[Pangoraw]

maybe something like this to prevent a trailing _ ?

Suggested change

	fname = mod_name === nothing ? "" : String(mod_name)
	fname = "module_" * lpad(MLIR_DUMP_COUNTER[], 3, "0") * "_$(fname)"
	fname = mod_name === nothing ? "" : "_" * String(mod_name)
	fname = "module_" * lpad(MLIR_DUMP_COUNTER[], 3, "0") * fname