make disabled send button background transparent

Fixes #1414

Signed-off-by: Andy Scherzinger <info@andy-scherzinger.de>

app/src/main/res/layout/controller_chat.xml

@@ -143,6 +143,8 @@
             app:attachmentButtonWidth="48dp"
             app:delayTypingStatus="200"
             app:inputButtonDefaultBgColor="@color/transparent"
+            app:inputButtonDefaultBgDisabledColor="@color/transparent"
+            app:inputButtonDefaultBgPressedColor="@color/transparent"
             app:inputButtonDefaultIconColor="@color/colorPrimary"
             app:inputButtonHeight="48dp"
             app:inputButtonMargin="0dp"

scripts/analysis/findbugs-results.txt

@@ -1 +1 @@
-436
+434