Always enable avatars

[MorrisJobke]

• we introduced this setting in the begining because our
  avatar support caused some performance issues, but we
  fixed them and should only provide one way how Nextcloud
  looks
• we have seen multiple issues with instances where avatars are disabled and it's not really a first class citizen UI experience
• fixes enable_avatars=false breaks sharing #3451

cc @nextcloud/designers @LukasReschke @rullzer @nickvergessen

[mention-bot]

@MorrisJobke, thanks for your PR! By analyzing the history of the files in this pull request, we identified @blizzz, @j-ed and @jancborchardt to be potential reviewers.

[skjnldsv]

Test restarted.

[codecov-io]

Codecov Report

Merging #3472 into master will decrease coverage by -0.09%.
The diff coverage is 78.26%.

@@             Coverage Diff              @@
##             master    #3472      +/-   ##
============================================
- Coverage     54.16%   54.07%   -0.09%     
- Complexity    21004    21227     +223     
============================================
  Files          1306     1306              
  Lines         80198    80482     +284     
  Branches       1255     1250       -5     
============================================
+ Hits          43437    43519      +82     
- Misses        36761    36963     +202

Impacted Files	Coverage Δ	Complexity Δ
core/templates/layout.user.php	0% <ø> (ø)	0 <ø> (ø)	❌
settings/templates/users/part.userlist.php	0% <ø> (ø)	0 <ø> (ø)	❌
lib/private/TemplateLayout.php	0% <ø> (ø)	32 <ø> (ø)	❌
settings/templates/personal.php	0% <ø> (ø)	0 <ø> (ø)	❌
settings/users.php	0% <ø> (ø)	0 <ø> (ø)	❌
config/config.sample.php	0% <ø> (ø)	0 <ø> (ø)	❌
settings/personal.php	0% <ø> (ø)	0 <ø> (ø)	❌
core/js/shareconfigmodel.js	69.56% <ø> (-8.7%)	0 <ø> (ø)
lib/private/Template/JSConfigHelper.php	0% <ø> (ø)	16 <ø> (ø)	❌
core/js/sharedialogshareelistview.js	65.83% <100%> (-0.22%)	0 <ø> (ø)
... and 9 more

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[jancborchardt]

Totally agree, it should be impossible to disable avatars. We use them everywhere and have placeholders too so it's pretty crucial.

[jancborchardt]

We need to make sure though that always when there is only an avatar, the image has an alt text for accessibility cc @nextcloud/accessibility @nextcloud/designers :)