Fix Qt5 warnings for using anchors

[luca-della-vedova]

I have been getting a lot of warnings being print out by Qt5 with the Component Inspector GUI plugin when clicking on models, specifically two warnings repeated many times:

[ign-8] [GUI] [Wrn] [Application.cc:649] [QT] file::/ComponentInspector/Pose3d.qml:132:9: QML Image: Detected anchors on an item that is managed by a layout. This is undefined behavior; use Layout.alignment instead.
[ign-8] [GUI] [Wrn] [Application.cc:649] [QT] file::/ComponentInspector/Vector3d.qml:93:9: QML Image: Detected anchors on an item that is managed by a layout. This is undefined behavior; use Layout.alignment instead.

This is way out of my comfort zone but by looking around I found some examples using Layout.alignment instead of anchors so went ahead to change the objects and the warnings disappeared.
As a sanity check this is what component inspector looks like with the changes:

There is a similar warning being caused by this line in the world-control plugin:

[ign-8] [GUI] [Wrn] [Application.cc:649] [QT] file::/WorldControl/WorldControl.qml:88:3: QML RoundButton: Detected anchors on an item that is managed by a layout. This is undefined behavior; use Layout.alignment instead.

If this fix is approved I'll open a PR to fix that warning as well.

[codecov]

Codecov Report

Merging #363 into master will increase coverage by 0.05%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #363      +/-   ##
==========================================
+ Coverage   77.16%   77.21%   +0.05%     
==========================================
  Files         200      200              
  Lines       10706    10706              
==========================================
+ Hits         8261     8267       +6     
+ Misses       2445     2439       -6     

Impacted Files	Coverage Δ
src/SimulationRunner.cc	94.76% <0.00%> (+1.16%)	⬆️

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[chapulina]

Nice, that had been annoying me too! Thanks for the fix!