fix(presentation): Fix navigation bar theming.

There is an issue for API levels below 27 where handling of light/dark
navigation bar cannot be handled. In these cases we need to use the
default black navigation bar.

presentation/src/main/res/values-v27/colors.xml

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright (c) 2022 Proton Technologies AG
+  ~ This file is part of Proton AG and ProtonCore.
+  ~
+  ~ ProtonCore is free software: you can redistribute it and/or modify
+  ~ it under the terms of the GNU General Public License as published by
+  ~ the Free Software Foundation, either version 3 of the License, or
+  ~ (at your option) any later version.
+  ~
+  ~ ProtonCore is distributed in the hope that it will be useful,
+  ~ but WITHOUT ANY WARRANTY; without even the implied warranty of
+  ~ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  ~ GNU General Public License for more details.
+  ~
+  ~ You should have received a copy of the GNU General Public License
+  ~ along with ProtonCore.  If not, see <https://www.gnu.org/licenses/>.
+  -->
+
+<resources>
+    <color name="nav_bar">@color/transparent</color>
+</resources>

presentation/src/main/res/values/colors.xml

@@ -168,7 +168,7 @@
 
     <!-- status & navigation bar color -->
     <color name="status_bar">@color/transparent</color>
-    <color name="nav_bar">@color/transparent</color>
+    <color name="nav_bar">@color/baltic_sea</color>
 
     <!-- Navigation view colors -->
     <color name="nav_view_background">@color/woodsmoke</color>