IDE updater bugfixes (#846)

* IDE updater assorted bugfix

- add linux AppImage target
- fix hardcoded if condition that causes to always show the update dialog
- fix redundant test build version
- recalculate sha512 after notarization on macOS

* boost notarization speed

* recalculate artifacts hash

arduino-ide-extension/src/node/ide-updater/ide-updater-impl.ts

@@ -58,10 +58,7 @@ export class IDEUpdaterImpl implements IDEUpdater {
     } = await this.updater.checkForUpdates();
 
     this.cancellationToken = cancellationToken;
-    if (
-      this.updater.currentVersion.compare(updateInfo.version) === -1 ||
-      true
-    ) {
+    if (this.updater.currentVersion.compare(updateInfo.version) === -1) {
       /*
         'latest.txt' points to the latest changelog that has been generated by the CI,
         so we need to make a first GET request to get the filename of the changelog