Improve Indexing Text Entries (#535)

Major
- Ensure search results logic consistent across migration to DB, multi-user
- Manually verified search results for sample queries look the same across migration
 - Flatten indexing code for better indexing progress tracking and code readability

Minor
- a4f407f Test memory leak on MPS device when generating vector embeddings
- ef24485 Improve Khoj with DB setup instructions in the Django app readme (for now)
- f212cc7 Arrange remaining text search tests in arrange, act, assert order
- 022017d Fix text search tests to test updated indexing log messages

pyproject.toml

@@ -93,6 +93,7 @@ test = [
     "factory-boy >= 3.2.1",
     "trio >= 0.22.0",
     "pytest-xdist",
+    "psutil >= 5.8.0",
 ]
 dev = [
     "khoj-assistant[test]",