The build process no longer relies on symlink

Change details:

• Removed all symlinks in $module/src/main/assets

• Introduce a new cmake install component "prebuilt-assets", can be enabled by

  fcitxComponent {
    installPrebuiltAssets = true
  }

  for plugins to install files from $PREBUILT_DIR (or other submodules) to apk assets

• Introduce a new dummy cmake target devel in :lib:fcitx5 module, and expose cmake config files from fcitx5 via its INTERFACE_INCLUDE_DIRECTORIES property

• Copy and minify ClearURLsRules/data.min.json by gradle script instead of just symlinking

• Configure aboutLibraries.configPath for all Android application modules in AndroidAppConventionPlugin