Linting with ruff

[mperrin]

• Added ruff config to pyproject.toml
• Many minor linting and code cleanup changes using ruff. No functional changes to STPSF are intended.
• This is intentionally only a partial & incomplete linting, an incremental change. In particular the files being revised for Roman in Adapt Roman code to new required data files #162 are intentionally not touched here, to avoid having to deal with conflicting edits when merging.