Check for FreeType functions required for avatars

[rullzer]

Fixes#7454

[ChristophWurst]

I'd prefer the shorter version

returnfunction_exists('imagettfbbox') && function_exists('imagettftext');

[rullzer]

fair enough

[codecov]

Codecov Report

Merging #7480 into master will increase coverage by <.01%.
The diff coverage is 60%.

@@ Coverage Diff @@## master #7480 +/- ##
============================================
+ Coverage 51.11% 51.11% +<.01% - Complexity 24901 24903 +2 
============================================
Files 1601 1601 Lines 94774 94778 +4 Branches 1367 1368 +1 ============================================
+ Hits 48441 48444 +3 - Misses 46333 46334 +1

Impacted Files	Coverage Δ	Complexity Δ
core/js/setupchecks.js	96.29% <100%> (+0.06%)	0 <0> (ø)	⬇️
settings/Controller/CheckSetupController.php	69.88% <33.33%> (-0.64%)	58 <2> (+2)
apps/files_trashbin/lib/Trashbin.php	72.28% <0%> (-0.25%)	136% <0%> (ø)
apps/user_ldap/lib/Access.php	35.74% <0%> (+0.04%)	315% <0%> (ø)	⬇️
lib/private/Files/Cache/Propagator.php	96.2% <0%> (+1.26%)	16% <0%> (ø)	⬇️

[ChristophWurst]

Looks good!

[danxuliu]

Tested on a system without FreeType support enabled and works as expected 👍

I have noticed, though, that not having FreeType support affects other elements besides just the avatars, for example the user settings UI (if you create a user or modify a user setting the UI will not be updated, although if you refresh the page you can see that it was modified as expected).

Maybe the error message should be something like "This will result in broken avatars and user settings UI" instead ("will" instead of "can" and "user settings UI" included in the message too)?

[rullzer]

@danxuliu I don't have a preference. Feel free to change the wording :)

[jancborchardt]

@danxuliu slightly improved:

This will result in broken profile pictures and settings interface.

(We call it »profile picture« in the settings, should not use »avatar« anywhere. Also, no technical abbreviation like »UI«.)

[danxuliu]

I have amended the commits with @jancborchardt suggestion, thanks!