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.

.github/workflows/user_scanner.yml

@@ -0,0 +1,40 @@
+name: Build user_scanner
+
+on:
+  push:
+    branches: [ "mian" ]
+    paths:
+      - '.github/workflows/user_scanner.yml'
+      - 'userspace/user_scanner/**'
+  workflow_dispatch:
+  workflow_call:
+    inputs:
+      target:
+        required: true
+        type: string
+      os:
+        required: false
+        type: string
+        default: self-hosted
+
+jobs:
+  build-user_scanner:
+    name: Build userspace user_scanner
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Build user_scanner
+        working-directory: ./userspace/user_scanner
+        run: |
+          $ANDROID_NDK_HOME/ndk-build
+
+      - name: Upload a Build Artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: userscanner-all-linux-android
+          path: ./userspace/user_scanner/libs