feat: add TestConnectionInfo for mobile

Adds TestConnectionInfo component which exposes some internal app state
to the jitsi-meet-torture through the UI accessibility layer. This
component will render only if config.testing.testMode is set to true.

react/features/testing/components/AbstractTestHint.js

@@ -0,0 +1,23 @@
+/* @flow */
+
+/**
+ * Describes the {@link TestHint}'s properties.
+ *
+ * A test hint is meant to resemble the lack of the ability to execute
+ * JavaScript by the mobile torture tests. They are used to expose some of
+ * the app's internal state that is not always expressed in a feasible manner by
+ * the UI.
+ */
+export type TestHintProps = {
+
+    /**
+     * The test hint's identifier string. Must be unique in the app instance
+     * scope.
+     */
+    id: string,
+
+    /**
+     * The test hint's (text) value which is to be consumed by the tests.
+     */
+    value: string
+}