i18n: support RTL languages

This patch introduces some mechanisms to fully support RTL languages:
1. RTL detection via UtilsAdapter::isRTL() checking the locale name
2. Using QML mirroring when needed based on UtilsAdapter.isRTL
3. Inverting panels in DualPaneView and JamiListView when needed
with SinglePane support

Moreover, lot of anchors are added to automatically manage layout
updates.

GitLab: #235
Change-Id: I40c245f2d7fae96d796c53505af5403f5e813e7f