[FEATURE] Streamline Template Buttons

This patch streamlines the behavior of template buttons. For this, we
sort all classes to match the same order. To be more flexible for the
usage of `DropDownButton` we now also allow the hiding of the label
text, but there must be a label text or an icon assigned.

We are introducing a `GenericButton` to cover more complex situations
while ensuring a unified output.

Adjust the `typo3-copy-to-clipboard` element to work like a normal
button element that allows keyboard navigation.

Resolves: #99806
Releases: main
Change-Id: Ic6e7d9036097bfd87493e51e5e128ab895af1731
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/77680


Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>