SystemUIs authorization (#1233)

* Initial implementation of AuthCodeStore for SystemUIs

* SystemUIs authorization

* Renaming SystemUI -> SignerUI

* Fixing clippy warnings

* Lowering time threshold

* Bumping sysui

* Fixing test

util/src/keys/directory.rs

@@ -465,7 +465,8 @@ pub struct KeyDirectory {
 	cache_usage: RwLock<VecDeque<Uuid>>,
 }
 
-fn restrict_permissions_owner(file_path: &Path) -> Result<(), i32>  {
+/// Restricts the permissions of given path only to the owner.
+pub fn restrict_permissions_owner(file_path: &Path) -> Result<(), i32>  {
 	let cstr = ::std::ffi::CString::new(file_path.to_str().unwrap()).unwrap();
 	match unsafe { ::libc::chmod(cstr.as_ptr(), ::libc::S_IWUSR | ::libc::S_IRUSR) } {
 		0 => Ok(()),