scripts : support arbitrary input file formats in compare-llama-bench.py

[CISC]

Refactored git/file handling into specialized classes to support arbitrary input file support.

For now it will fall back to JSONL if sqlite fails, but there is also support for (multiple) JSON and CSV files (see FIXME for the latter though).

[CISC]

I think we should not have two parallel implementations for fetching data; either sqlite data should be using the generic implementation or JSON/JSONL data should be used to fill an SQL database. My personal preference would be SQL but I am willing to compromise depending on what other maintainers prefer.

Hm, ok, so an in-memory database then?

[JohannesGaessler]

Yes.

[CISC]

Ok, done.