GPS refactor & license text updates (#601)

- Split up `gps-generic-module` into:
  - `gps-generic-module` that contains only interfaces/configs/bindings (Apache license)
  - `gps-meshtastic-module` that contains an implementation (GPL license)
- Update `LICENSE.md` for changes, but also added clarifications
- Added licenses to directories where they were missing
- Changed license of some test projects from GPL to Apache.

Drivers/gps-generic-module/include/gps_generic/module.h

@@ -0,0 +1,12 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+#pragma once
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+extern struct Module gps_generic_module;
+
+#ifdef __cplusplus
+}
+#endif