[stable12] Use PNG icons for activity emails and ios client

[nickvergessen]

Backport #5483

• Activity app PR: [stable12] Use PNG icons for emails and ios client activity#176

[MorrisJobke]

Tested and works 👍

[ArtificialOwl]

This was yesterday on master

---

This is today on stable12

[ArtificialOwl]

looks like an issue with the webmail client, original mail on the server contains the right img src=""

[codecov]

Codecov Report

Merging #5648 into stable12 will decrease coverage by 0.13%.
The diff coverage is 4.71%.

@@ Coverage Diff @@## stable12 #5648 +/- ##
==============================================
- Coverage 54.19% 54.05% -0.14% - Complexity 22358 22442 +84 
==============================================
Files 1379 1379 Lines 85556 85769 +213 Branches 1329 1329 ==============================================
+ Hits 46363 46365 +2 - Misses 39193 39404 +211

Impacted Files	Coverage Δ	Complexity Δ
...es_sharing/lib/Activity/Providers/RemoteShares.php	0% <0%> (ø)	17 <0> (+2)	⬆️
...files_sharing/lib/Activity/Providers/Downloads.php	0% <0%> (ø)	17 <0> (+2)	⬆️
...pps/files_sharing/lib/Activity/Providers/Users.php	0% <0%> (ø)	23 <0> (+2)	⬆️
apps/dav/lib/CalDAV/Activity/Provider/Todo.php	0% <0%> (ø)	25 <0> (+1)	⬆️
apps/files/lib/Activity/FavoriteProvider.php	0% <0%> (ø)	18 <0> (+4)	⬆️
apps/files/lib/Activity/Provider.php	13.69% <0%> (-3.85%)	71 <0> (+16)
apps/systemtags/lib/Activity/Provider.php	0% <0%> (ø)	41 <0> (+2)	⬆️
apps/sharebymail/lib/Activity.php	0% <0%> (ø)	39 <0> (+8)	⬆️
...ps/files_sharing/lib/Activity/Providers/Groups.php	0% <0%> (ø)	17 <0> (+2)	⬆️
apps/comments/lib/Activity/Provider.php	5.82% <0%> (-0.18%)	22 <0> (+1)
... and 11 more