Add UID scanner functionality and related infrastructure

- Introduced a new module `uid_scanner` in userspace for managing UID scanning.
- Created a new GitHub Actions workflow for building the `user_scanner`.
- Implemented kernel communication in `throne_comm.c` and `throne_comm.h` to handle user space updates and rescan requests.
- Developed the `uid_scanner` daemon in C to scan user directories and manage UID whitelists.
- Added configuration management for the UID scanner with support for multiple users and auto-scanning.
- Implemented logging and error handling throughout the UID scanning process.
- Created necessary build files for the `user_scanner` JNI integration.
- Added a `.gitignore` file to exclude build artifacts.

kernel/throne_comm.h

@@ -0,0 +1,12 @@
+#ifndef __KSU_H_THRONE_COMM
+#define __KSU_H_THRONE_COMM
+
+void ksu_request_userspace_scan(void);
+
+void ksu_handle_userspace_update(void);
+
+int ksu_throne_comm_init(void);
+
+void ksu_throne_comm_exit(void);
+
+#endif