Allow environmental variable to set cache path for speechbrain and brouhaha

[ajkessel]

This repo has several hardcoded paths for cache directories, e.g. 1 e.g. 2 . huggingface respects the HF_HOME environment variable for caching models, but there is no way to do anything similar with the current code for speechbrain and brouhaha. Would you consider allowing an environmental variable as an alternative to the hardcoded home directory? Or perhaps read XDG_CACHE_HOME for .cache mapping?