hooks: more rhai fs functions

[BrettMayson]

• .list() array of files in a directory
• .file_name() returns the file / dir name
• .parent() returns the parent of the path
• HEMTT.project().mainprefix(), return main prefix or empty string if not set

[codecov]

Codecov Report

Merging #593 (882b6cd) into main (960f55b) will decrease coverage by 0.4%.
Report is 1 commits behind head on main.
The diff coverage is 40.9%.

Files	Coverage Δ
bin/src/modules/hook/mod.rs	93.2% <100.0%> (ø)
bin/src/error.rs	0.0% <0.0%> (ø)
bin/src/modules/hook/libraries/project.rs	65.3% <57.1%> (-3.1%)	⬇️
bin/src/modules/hook/libraries/rfs/path.rs	76.1% <76.4%> (-0.8%)	⬇️
bin/src/modules/hook/libraries/vfs/path.rs	1.9% <0.0%> (-0.9%)	⬇️

... and 7 files with indirect coverage changes