Add capability to request username creation during registration.

app/src/main/java/org/thoughtcrime/securesms/components/ProgressCard.kt

@@ -0,0 +1,22 @@
+package org.thoughtcrime.securesms.components
+
+import android.content.Context
+import android.util.AttributeSet
+import com.google.android.material.card.MaterialCardView
+import org.thoughtcrime.securesms.R
+
+/**
+ * A small card with a circular progress indicator in it. Usable in place
+ * of a ProgressDialog, which is deprecated.
+ *
+ * Remember to add this as the last UI element in your XML hierarchy so it'll
+ * draw over top of other elements.
+ */
+class ProgressCard @JvmOverloads constructor(
+  context: Context,
+  attrs: AttributeSet? = null
+) : MaterialCardView(context, attrs) {
+  init {
+    inflate(context, R.layout.progress_card, this)
+  }
+}