[fenix] For https://github.com/mozilla-mobile/fenix/issues/9605: TestApplication -> FenixRobolectricTestApplication.

This disambiguates it from the FirefoxTestApplication used in on-device
tests.

app/src/test/java/org/mozilla/fenix/helpers/FenixRobolectricTestApplication.kt

@@ -7,7 +7,10 @@ package org.mozilla.fenix.helpers
 import org.mozilla.fenix.FenixApplication
 import org.mozilla.fenix.components.TestComponents
 
-class TestApplication : FenixApplication() {
+/**
+ * An override of our application for use in Robolectric-based unit tests.
+ */
+class FenixRobolectricTestApplication : FenixApplication() {
 
     override val components = TestComponents(this)
 

app/src/test/java/org/mozilla/fenix/helpers/FenixRobolectricTestRunner.kt

@@ -25,7 +25,7 @@ class FenixRobolectricTestRunner(testClass: Class<*>) : RobolectricTestRunner(te
 
     override fun buildGlobalConfig(): Config {
         return Config.Builder()
-            .setApplication(TestApplication::class.java)
+            .setApplication(FenixRobolectricTestApplication::class.java)
             .build()
     }
 }