`ForceFunctionAttrs`: support overriding attributes via csv file

Update `ForceFunctionAttrs` pass to optionally take its input from a csv file, for example, function-level optimization attributes. A subsequent patch will enable the pass pipeline to be aware of these attributes, and this pass will be used to test that is the case. Eventually, the annotations would be driven by an agent, e.g. a machine learning-based policy.

This patch is a part of GSoC 2023, more details can be found [[ https://summerofcode.withgoogle.com/programs/2023/projects/T8rB84Sr | here ]]

Reviewed By: mtrofin, aeubanks

Differential Revision: https://reviews.llvm.org/D155617