feat: Add a unit test target (jest) to the UI extension and run it in CI (#1192)

- Introduce test targets.
- Adding additional tests.

Related to: https://github.com/harvester/harvester/issues/11892

Signed-off-by: Volker Theile <vtheile@suse.com>

vue3JestRegisterTs.js

@@ -0,0 +1,15 @@
+/**
+ * Unit tests are failing with the following error:
+ *
+ * ```
+ *     [@vue/compiler-sfc] No fs option provided to `compileScript` in non-Node environment. File system access is required for resolving imported types.
+ * ```
+ *
+ * It seems TypeScript does not populate ts.sys when loaded in Jest. In order to
+ * resolve this issue, we can use the hack below to point to a different
+ * transformer than vue-jest and call registerTs before exporting vue-jest.
+ *
+ * SEE: https://github.com/vuejs/core/issues/8301
+ */
+require('@vue/compiler-sfc').registerTS(() => require('typescript'));
+module.exports = require('@vue/vue3-jest');