[4.0] Revert #26056, solving dropdown batch icon and add module icon

[infograf768]

Pull Request for Issue #26741

Summary of Changes

Reverts #26056
Changed fa fa-square to icon-square to solve that batch dropdown icon display issue. THanks @Quy :)
Correct alignment of the Dashboard add module

Testing Instructions

Patch. Run npm.
Display /administrator/index.php and ckeck quickicons alignment are correctly centered as well as the Add module to the dashboard icon.

Display the Content Dashboard and check the alignment of the + icon

Display the Article manager, select an article and check the alignment of the Batch icon.

Before patch

See #26741

After patch

[C-Lodder]

Ideally you want to start moving all core to the fa class (seeing as svg's won't be accepted). The fa and icon classes should adopt the same CSS (as they are simply mapped rather than a different font set), so there should be no difference between the classes.

I'd suggest finding and properly fixing the core root of the actual problem rather than trying to cover it up

[infograf768]

@C-Lodder
I agree this would be ideal.
I also think it has to be done in a specific PR and I have no idea how to do that.
In the mean while let's just have things work as should as #26056 broke all and I can't make RTL corrections without it.

[Quy]

I have tested this item ✅ successfully on 30aee16

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[richard67]

I have tested this item ✅ successfully on 30aee16

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/26757.}

[Quy]

RTC

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/26757.}