NXDRIVE-1926: Improve the Direct Transfer window

[BoboTiG]

• Reworked the entire window to place elements "correctly" (each element has its own rectangle, it eases positioning and thinking).
• The scrollbar is only affecting the items list: this allowes to not hide the selected remote folder on scrolling.
• Fixed the window resizing that was very weird and sometimes it was also not possible to resize it.
• Introduced tabs for next works, it renders better IMO.
• Commented the QML code to ease maintenance and reading.
• Fixed a QML error on Windows:

QWindowsWindow::setGeometry: Unable to set geometry 580x220+660+390 (frame: 598x267+651+352)
on QQuickView/"" on "\\.\DISPLAY1". Resulting geometry: 600x300+660+390
(frame: 618x347+651+352) margins: 9, 38, 9, 9 minimum size: 600x300
MINMAXINFO maxSize=0,0 maxpos=0,0 mintrack=618,347 maxtrack=0,0)

[nuxeojenkins]

View issue in JIRA: NXDRIVE-1926: [Direct Transfer] Display global transfer metrics

[sourcery-ai]

Sourcery Code Quality Report (beta)

Merging this PR leaves code quality unchanged.

	Before	After	Change
Quality	8.21	8.21	0.0
Complexity	2.21	2.21	0.0
Method Length	76.61	76.61	0.0
Lines	1670	1670	0

Changed files	Quality Before	Quality After	Quality Change
nxdrive/gui/application.py	8.21	8.21	0.0

Here are some functions in these files that still need a tune-up:

File	Function	Quality	Recommendation
nxdrive/gui/application.py	Application.init_gui	4.6	Split out functionality
nxdrive/gui/application.py	Application.__init__	5.06	Split out functionality
nxdrive/gui/application.py	Application.accept_unofficial_ssl_cert	5.16	Split out functionality
nxdrive/gui/application.py	Application.confirm_deletion	5.34	Split out functionality
nxdrive/gui/application.py	Application._fill_qml_context	5.38	Split out functionality

Please see our documentation here for details on how these metrics are calculated.

We are actively working on this report - lots more documentation and extra metrics to come!

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