Add helper components for UI

Changes:
- Extracted Copyright from LoginDialog file to its own
- Added some helper components
- Removed unnecessary setup from welcome animation
- Added custom React type for svg element
- Fixed ThemeDemonstrator

GitLab: #12
Change-Id: Ie7158520983dab5c7069f179b6f9531b5106ba85
diff --git a/client/src/components/ProcessingRequest.tsx b/client/src/components/ProcessingRequest.tsx
new file mode 100644
index 0000000..c7da9a4
--- /dev/null
+++ b/client/src/components/ProcessingRequest.tsx
@@ -0,0 +1,27 @@
+/*
+ * Copyright (C) 2022 Savoir-faire Linux Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation; either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public
+ * License along with this program.  If not, see
+ * <https://www.gnu.org/licenses/>.
+ */
+import Backdrop from '@mui/material/Backdrop';
+import CircularProgress from '@mui/material/CircularProgress';
+
+export default function ProcessingRequest(props: { open: boolean }) {
+  return (
+    <Backdrop sx={{ color: '#fff', zIndex: (theme) => theme.zIndex.drawer + 1 }} open={props.open} onClick={() => {}}>
+      <CircularProgress color="inherit" />
+    </Backdrop>
+  );
+}