feat: meilisearch backend for notes search

This is a very simple and basic backend. It is based on Django signals,
just like the Elasticsearch backend. But it is much simpler, in the
sense that there are just two signals: one for saving documents and one
for deletion.

This backend is limited, in the sense that it does not support
highlighting -- but that's probably not such a big deal.

To start using this backend, define the following settings:

	ES_DISABLED = True
	MEILISEARCH_ENABLED = True
	MEILISEARCH_URL = "http://meilisearch:7700"
	MEILISEARCH_API_KEY = "s3cr3t"
	MEILISEARCH_INDEX = "tutor_student_notes"

notesapi/v1/views/__init__.py

@@ -8,12 +8,17 @@
 
 from .exceptions import SearchViewRuntimeError
 
+
+# pylint: disable=import-outside-toplevel
 def get_views_module():
     """
     Import views from either mysql or elasticsearch backend
     """
     if settings.ES_DISABLED:
-        from . import common as backend_module
+        if getattr(settings, "MEILISEARCH_ENABLED", False):
+            from . import meilisearch as backend_module
+        else:
+            from . import common as backend_module
     else:
         from . import elasticsearch as backend_module
     return backend_module