Docker compose plugins fix (#3357)

* Simplify dockerfile - remove INVENTREE_DEV_DIR

- We can simply use INVENTREE_DATA_DIR
- Will need to update the documentation

* Remove plugin dir support from production docker-compose file

docker-compose.yml

@@ -55,7 +55,6 @@ services:
         volumes:
             # Ensure you specify the location of the 'src' directory at the end of this file
             - inventree_src:/home/inventree
-            - inventree_plugins:/home/inventree/InvenTree/plugins
         env_file:
             - .env
         restart: unless-stopped
@@ -70,7 +69,6 @@ services:
         volumes:
             # Ensure you specify the location of the 'src' directory at the end of this file
             - inventree_src:/home/inventree
-            - inventree_plugins:/home/inventree/InvenTree/plugins
         env_file:
             - .env
         restart: unless-stopped
@@ -104,10 +102,3 @@ volumes:
             # This directory specified where InvenTree source code is stored "outside" the docker containers
             # By default, this directory is one level above the "docker" directory
             device: ${INVENTREE_EXT_VOLUME:-./}
-    inventree_plugins:
-        driver: local
-        driver_opts:
-          type: none
-          o: bind
-          # This directory specified where the optional local plugin directory is stored "outside" the docker containers
-          device: ${INVENTREE_EXT_PLUGINS:-../InvenTree/plugins}