This PR adds the ability for icon themes to provide their own file
associations.
The old `file_types.json` that was previously used to make these
associations has been removed in favor of storing them on the default
theme.
Icon themes have two new fields on them:
- `file_stems`: A mapping of file stems to icon keys.
- `file_suffixes`: A mapping of file suffixes to icon keys.
These mappings produce icon keys which can then be used in `file_icons`
to associate them to a particular icon:
```json
{
"file_stems": {
"Makefile": "make"
},
"file_suffixes": {
"idr": "idris"
},
"file_icons": {
"idris": { "path": "./icons/idris.svg" },
"make": { "path": "./icons/make.svg" }
}
}
```
When loading an icon theme, the `file_stems` and `file_icons` fields
will be merged with the ones from the base icon theme, with the values
from the icon theme being loaded overriding ones in the base theme.
Release Notes:
- Added the ability for icon themes to provide their own file
associations.