Add some polish to the groups V2 manager UI.

app/src/main/java/org/thoughtcrime/securesms/util/StringUtil.java

@@ -0,0 +1,31 @@
+package org.thoughtcrime.securesms.util;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import java.nio.charset.StandardCharsets;
+
+public final class StringUtil {
+
+  private StringUtil() {
+  }
+
+  /**
+   * Trims a name string to fit into the byte length requirement.
+   */
+  public static @NonNull String trimToFit(@Nullable String name, int maxLength) {
+    if (name == null) return "";
+
+    // At least one byte per char, so shorten string to reduce loop
+    if (name.length() > maxLength) {
+      name = name.substring(0, maxLength);
+    }
+
+    // Remove one char at a time until fits in byte allowance
+    while (name.getBytes(StandardCharsets.UTF_8).length > maxLength) {
+      name = name.substring(0, name.length() - 1);
+    }
+
+    return name;
+  }
+}