use local modules if main.py is run directly.

When west/app/main.py is executed directly, also the correct West
modules must be imported. Therefore, the Python module search path is
configured appropriately before importing any West modules.

Author: thorsten-klein

src/west/app/main.py

@@ -30,6 +30,13 @@
 
 import colorama
 
+if __name__ == "__main__":
+    # Prepend the west src directory to sys.path so that running this script
+    # directly in a local tree always uses the according local 'west' modules
+    # instead of any installed modules.
+    src_dir = Path(__file__).resolve().parents[2]
+    sys.path.insert(0, os.fspath(src_dir))
+
 import west.configuration
 from west import log
 from west.app.config import Config