Rust: make the cli flags override automatic

[redsun82]

This makes the clap flags overlay over Config entirely derived via an attribute macro. Also, the --intputs-file option is replaced by a more standard and versatile @ parameter file mechanism.

[aibaars]

This looks great. Have you checked that the CODEQL_EXTRACTOR_RUST_OPTION prefix overrides ``CODEQL_EXTRACTOR_RUST_? We may also want to addCODEQL_` as a lower priority prefix, so that things like `CODEQL_VERBOSITY` is picked up, but can be overridden by setting `CODEQL_EXTRACTOR_VERBOSITY`.

[redsun82]

This looks great. Have you checked that the CODEQL_EXTRACTOR_RUST_OPTION prefix overrides ``CODEQL_EXTRACTOR_RUST_? We may also want to add CODEQL_` as a lower priority prefix, so that things like `CODEQL_VERBOSITY` is picked up, but can be overridden by setting `CODEQL_EXTRACTOR_VERBOSITY`.

Yes, Figment merge gives an ordering of source priority, which means that CODEQL_EXTRACTOR_RUST_OPTION_* has precedence over CODEQL_EXTRACTOR_RUST_* (and now over CODEQL_* as you suggested). And CLI flags (when passed) have priority over all else. The tricky part solved by the macro is to not have CLI flag defaults override env variables (which is what the skip_serializing_if are for).

[aibaars]

Looks good to me. Any idea why Python tests would be failing for this pull request?

[redsun82]

Looks good to me. Any idea why Python tests would be failing for this pull request?

Discussing it on slack, but in the meantime a rerun worked 🤷