add cache_dir and local_dir parameters

[BBC-Esq]

This pull request is related (but not identical) to #863

It builds upon the other pull request adding a local_dir parameter, allowing the download of the repository NOT IN BLOB form:

Summary

Source	Parameters	Behavior	File Structure	Hash Verification
"huggingface"	(default)	Downloads to ~/.cache/huggingface	Cache structure	Yes
"huggingface"	cache_dir="path"	Downloads to specified path	Cache structure	Yes
"huggingface"	local_dir="path"	Downloads to specified path	Original repo structure	No
"local"	(default)	Downloads to current directory	Cache structure	Yes
"local"	cache_dir="path"	Downloads to specified path	Cache structure	Yes
"local"	local_dir="path"	Downloads to specified path	Original repo structure	No
"custom"	custom_path="path"	Uses existing files	As provided	Yes
"custom"	custom_path + cache_dir	cache_dir ignored	As provided	Yes
"custom"	custom_path + local_dir	local_dir ignored	As provided	Yes