Templated hooks we almost completely useless, so we get rid of them.
This allows us to get rid entirely of hook names and hook indexes, which
makes the whole implementation much simpler. Hook removal (with
`clear_all`) is achieved thanks to weak references.
The hooks API had several issues which are summarized in this comment:
https://github.com/openedx/wg-developer-experience/issues/125#issuecomment-1313553526
1. "consts" was a bad name
2. "hooks.filters" and "hooks.Filters" could easily be confused
3. docs made it difficult to understand that plugin developers should use the catalog
To address these issues, we:
1. move "consts.py" to "catalog.py"
2. Remove "hooks.actions", "hooks.filters", "hooks.contexts" from the API.
3. re-organize the docs and give better usage examples in the catalog.
This change is a partial fix for https://github.com/openedx/wg-developer-experience/issues/125
