Remove temp cut buffer commands and cleanup related SourceView code

- Moved cut_to_temp_buffer and paste_temp_buffer commands to plugin
- Remove temp buffer state and timeout logic from SourceView
- Remove associated keybindings (Ctrl+K / Ctrl+U)
- Ignore "buffer" pseudo-path when filtering loaded files
- Ensure view receives focus after DnD file load

plugins/code/commands/nanoesq_temp_buffer/plugin.py

@@ -0,0 +1,43 @@
+# Python imports
+
+# Lib imports
+
+# Application imports
+from libs.event_factory import Event_Factory, Code_Event_Types
+
+from plugins.plugin_types import PluginCode
+
+from .cut_to_temp_buffer import Handler
+from .paste_temp_buffer import Handler2
+
+
+
+class Plugin(PluginCode):
+    def __init__(self):
+        super(Plugin, self).__init__()
+
+
+    def _controller_message(self, event: Code_Event_Types.CodeEvent):
+        ...
+
+    def load(self):
+        event = Event_Factory.create_event("register_command",
+            command_name = "cut_to_temp_buffer",
+            command      = Handler,
+            binding_mode = "held",
+            binding      = "<Control>k"
+        )
+
+        self.emit_to("source_views", event)
+
+        event = Event_Factory.create_event("register_command",
+            command_name = "paste_temp_buffer",
+            command      = Handler2,
+            binding_mode = "held",
+            binding      = "<Control>u"
+        )
+
+        self.emit_to("source_views", event)
+
+    def run(self):
+        ...