TB 43243: [android] Implement Android launch test

Also remove exit call from terminate function.
It causes all espresso tests to crash on exit and otherwise doesn't do anything.

mobile/android/fenix/app/src/androidTest/java/org/mozilla/fenix/AppStartupTest.kt

+package org.mozilla.fenix
+
+import androidx.test.ext.junit.rules.ActivityScenarioRule
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import androidx.test.platform.app.InstrumentationRegistry
+import androidx.test.uiautomator.UiDevice
+import org.junit.Rule
+import org.junit.Test
+import org.junit.runner.RunWith
+import java.util.concurrent.CountDownLatch
+import java.util.concurrent.TimeUnit
+
+
+@RunWith(AndroidJUnit4::class)
+class LaunchTest {
+
+    @get:Rule
+    var rule: ActivityScenarioRule<HomeActivity> = ActivityScenarioRule(HomeActivity::class.java)
+
+    @Test
+    fun appLaunchesWithoutCrash() {
+        val device = UiDevice.getInstance(InstrumentationRegistry.getInstrumentation())
+        device.waitForIdle()
+
+        // Simulate a 30-second delay
+        val latch = CountDownLatch(1)
+        Thread {
+            try {
+                Thread.sleep(30_000)
+                latch.countDown()
+            } catch (e: InterruptedException) {
+                e.printStackTrace()
+            }
+        }.start()
+
+        latch.await(30, TimeUnit.SECONDS)
+
+        // If we got here, the app did not crash. Test passed.
+    }
+}