Add Bluetooth LE functionality to bttestui

Bttestui is a manual bluetooth test application with which one can
manually test different bluetooth features. This commit adds Low Energy
support for the application.

The support is logically simple and flat meaning that it does not
on purpose implement automated state flows. Rather one can manually
trigger each action and modify them locally as needed for testing
purposes.

The commit adds base support for both central and peripheral roles and
their basic functionalities: discovery, advertisement, read and write.

In addition few changes:
- Make the main.qml flickable to be able to use on small screens
- Remove QML import numbering
- Add nullptr checks in some of the functions, sometimes it is
  intentional to eg. disable localDevice creation

Fixes: QTBUG-103827
Change-Id: I57c88912803eab8e777c9e6ef3bcaa5401709381
Reviewed-by: Ivan Solovev <ivan.solovev@qt.io>

0 files changed, 0 insertions, 0 deletions