Allow to silence Info messages

[spotlesscoder]

Feature Description

I am reorganizing my library and deleting tracks from disk out of mixxx

The message itself is helpful but not at the moment
I likely won't remember the fact after a few weeks
So to silence it only temporarily, I want a checkbox "don't show again" followed by a dropdown select box with "1 hour", "6 hours", "24 hours"

[ronso0]

This can be implemented somewhere here

mixxx/src/widget/wtrackmenu.cpp

Line 2434 in c0b4f50

 msgBoxPurgeTracks.setWindowTitle(msgTitle); 

A similiar implementation exists for the Hide / Remove from Playlist/Crate views

mixxx/src/widget/wtracktableview.cpp

Line 1217 in c0b4f50

 QCheckBox notAgainCB(tr("Don't ask again during this session")); 

though that stores the check state in the trackmodels.
For the Move to Trash function in WTrackMenu (available with and without trackmodel) we need to use a static bool in WTrackMenu.

I suggest to allow suppressing the dialog only for the current session first. A fixed suspend time is certainly possible, too, probabaly also via a static variable (int, double) storing the time when the "Don't show" checkbox is ticked.

[spotlesscoder]

I like the idea of suspending for the current session only :)

Actually I like it more than my idea - probably a bit easier to implement, too