bios cradle should not interpret the program path relative to the cwd

The path of the program attribute is interpreted relative to the current working directory if it isn't absolute. A program is passed the file to return options for as its first argument, and a shell command will have it available in the HIE_BIOS_ARG environment variable.

This is odd because the writer of the hie.yaml file has no influence on what the editor passes as the root dir of the current project, i.e. it is not possible to know statically. That is why I think all relative paths should be made absolute in relation to where the hie.yaml file lives.

(Making the path a priori absolute might also not be possible, for obvious reasons)