feat(tauri): Initialize Context in background (#59)

This PR does the following:
- The Context (including Bitcoin wallet, Monero wallet, ...) is initialized in the background. This allows the window to be displayed instantly upon startup.
- Host sends events to Guest about progress of Context initialization. Those events are used to display an alert in the navigation bar.
- If a Tauri command is invoked which requires the Context to be available, an error will be returned
- As soon as the Context becomes available the `Guest` requests the history and Bitcoin balance
- Re-enables Material UI animations

src-gui/src/renderer/components/modal/swap/pages/init/InitPage.tsx

@@ -72,6 +72,7 @@ export default function InitPage() {
         className={classes.initButton}
         endIcon={<PlayArrowIcon />}
         onClick={init}
+        displayErrorSnackbar
       >
         Start swap
       </PromiseInvokeButton>