establish a pattern for node which store user data and make sure all custom-nodes are patched to follow it

[adrian-gierakowski]

some nodes read\write their own data

these nodes often expect to be able to write to the directory in which they are installed, which is obviously not possible in our case since nodes' source is in /nix/store

it would be good to establish a pattern for the nodes to use a single (user configurable) directory, with sub-dir for each node
this could default to $DATA_HOME/user/default (some nodes already use this btw).

[M3L6H]

I guess #149 is related to this. Since we have to patch the custom nodes to make this work, how can we make the directory user configurable?

[typedrat]

currently hitting this with the tag autocomplete in pythongosssss-custom-scripts, when trying to download a new tag list.