Moved plugins and add loaded file filtering

- Moved prettify_json and lsp_completer plugins to sub categories
- Add filter_out_loaded_files to prevent opening already-loaded files
- Refactor code events into single events module
- Fix signal blocking during file load operations
- Include READONLY state in source view lifecycle handling

plugins/code/event-watchers/file_state_watcher/watcher_checks.py

@@ -0,0 +1,32 @@
+# Python imports
+
+# Lib imports
+import gi
+gi.require_version('Gtk', '3.0')
+from gi.repository import Gtk
+
+# Application imports
+from libs.event_factory import Event_Factory, Code_Event_Types
+
+
+
+def file_is_deleted(event):
+    event.file.was_deleted = True
+    event = Event_Factory.create_event(
+        "file_externally_deleted",
+        file   = event.file,
+        buffer = event.buffer
+    )
+    self.emit(event)
+
+
+def file_is_externally_modified(event):
+#    event = Event_Factory.create_event(
+#        "file_externally_modified",
+#        file   = event.file,
+#        buffer = event.buffer
+#    )
+#    self.emit(event)
+
+    ...
+