Index more text file types from Desktop, Github (#692)

### Index more text file types 
- Index all text, code files in Github repos. Not just md, org files
- Send more text file types from Desktop app and improve indexing them
- Identify file type by content & allow server to index all text files

### Deprecate Github Indexing Features
- Stop indexing commits, issues and issue comments in a Github repo
- Skip indexing Github repo on hitting Github API rate limit

### Fixes and Improvements
- **Fix indexing files in sub-folders from Desktop app**
- Standardize structure of text to entries to match other entry processors

pyproject.toml

@@ -46,6 +46,7 @@ dependencies = [
     "openai >= 1.0.0",
     "tiktoken >= 0.3.2",
     "tenacity >= 8.2.2",
+    "magika ~= 0.5.1",
     "pillow ~= 9.5.0",
     "pydantic >= 2.0.0",
     "pyyaml ~= 6.0",