Bld/inc input data

[tacaswell]

@briantoby The most of the files in inputs should now be installed.

[briantoby]

Tracking develop branch issues:

• pixi run install-editable does not place compiled programs convcell & LATTIC into .pixi/envs//bin; (N.B. pixi run install does do this)

• comment in GSASIIphsGUI.py: "XXX I suspect this is Unix-specific -- need porting help!". Is this still relevant?

• Best way to read & write configuration info to an external file?

  N.B. to replace config.py but not config_example.py; What is best choice? tomllib/tomli/tomli-w or configparser or something else?

• running tests/test_scripting.py fails due to "path hacking"; problem seems to be within pytest, but is not seen with the other self-tests.