Make darktable executables handle --help option consistently

Is your feature request related to a problem? Please describe.

This is a minor irritation.

There are a number of darktable executables, and they don't all handle --version and --help the same way. For instance I have

1. darktable - both options behave well
2. darktable-chart: --help is doesn't say what the executable actually does, just what the options are, --version complains there is no such file
3. darktable-cli - both options behave well
4. darktable-cltest - both options behave well
5. darktable-cmstest - options appear to be ignored (same output with or without any options)
6. darktable-generate-cache - both options behave well
7. darktable-mcp - options are ignored and executable sits waiting for input (at least, that is what I guess it is doing)
8. darktable-rs-identify - both options result in an error about not finding the file

Describe the solution you'd like

Consistent handling of --help and --version.

Alternatives

Additional context

Start by running each listed executable with --help and --version, comparing the current output and behavior, especially darktable-chart, darktable-cmstest, darktable-mcp, and darktable-rs-identify. Trace the executable entry points for these tools and make their option handling consistent with the working examples; done means both options produce appropriate output without treating them as input files or waiting for input.