Feat: Upload Files (#59)

This MR adds the ability to add files to comments, notes, replys, and MR descriptions via a picker.

The file will get uploaded to Gitlab and the filepath will be automatically added into the current popup buffer at the current line. You can then save the changes with the normal save functionality.

todo.md

@@ -1,5 +1,8 @@
 ## Todo
 
-- [ ] Fix the u.merge function to avoid overwriting settings
-- [ ] Finish the Reply functionality
-- [ ] Auto-Pick buffer when Cycling Through Comments
+- Screenshot folder in config (where the images will be kept)
+- Within the Summary view, you can call the add_summary_image() command
+- This command will open a UI picker to choose the file
+- When you choose the file, we pass that file path to an API endpoint which uploads
+the file and returns the JSON in the API here (https://docs.gitlab.com/ee/api/projects.html#upload-a-file)
+- Then we write that into the Summary buffer at the current cursor