Added Snackbar qtquick object

[ahcorde]

🎉 New feature

Summary

Create a IgnSnackBar QtQuick object to show message to the user in the same manner by plugins

It could be :

• persistant and then you need to click inside the GUI
• or with a timeout

Added snackbar dialog to:

• Save configuration
• Teleop topic
• Snapshot
• Image view update

Checklist

• Signed all commits for DCO
• Added tests
• Added example and/or tutorial
• Updated documentation (as needed)
• Updated migration guide (as needed)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
• While waiting for a review on your PR, please help review another open pull request to support the maintainers

Note to maintainers: Remember to use Squash-Merge and edit the commit message to match the pull request summary while retaining Signed-off-by messages.

[codecov]

Codecov Report

Merging #369 (eb58ef3) into ign-gui3 (fc2f870) will decrease coverage by 0.13%.
The diff coverage is 38.46%.

@@             Coverage Diff              @@
##           ign-gui3     #369      +/-   ##
============================================
- Coverage     65.96%   65.83%   -0.14%     
============================================
  Files            29       29              
  Lines          3191     3202      +11     
============================================
+ Hits           2105     2108       +3     
- Misses         1086     1094       +8     

Impacted Files	Coverage Δ
include/ignition/gui/MainWindow.hh	100.00% <ø> (ø)
src/plugins/screenshot/Screenshot.cc	30.12% <0.00%> (-3.22%)	⬇️
src/plugins/teleop/Teleop.cc	83.19% <37.50%> (-1.77%)	⬇️
src/plugins/image_display/ImageDisplay.cc	24.07% <66.66%> (+0.80%)	⬆️

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[chapulina]

+1 to the centralized approach using a signal from the MainWindow 👍 This should make it easier to improve the snackbar in the future. For example, in the future, if we start getting too many notifications at once, we may want to implement some logic to display them consecutively.

[chapulina]

LGTM! I just pushed a small change in eb58ef3 to change the border to a shadow.

Before:

After:

[osrf-triage]

This pull request has been mentioned on Gazebo Community. There might be relevant details there:

https://community.gazebosim.org/t/new-ignition-releases-2022-04-13-fortress-edifice/1367/1