Use IUser

[LukasReschke]

This is broken and will never work as the phan CI step pointed out at https://drone.nextcloud.com/nextcloud/server/523/48

lib/private/Share20/Manager.php:720 PhanUndeclaredClassInstanceof Checking instanceof against undeclared class \OC\Share20\IUser

Pro-tip of the day: Check why CI fails before merging 🙈

Looking at @MorrisJobke and @rullzer for a review 😉

[MorrisJobke]

Ref #5897

[MorrisJobke]

This is broken and will never work

PHP has forgiven this and just continued 🙈 It actually worked, but has written a warning 🙈

[codecov]

Codecov Report

Merging #5949 into master will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master    #5949   +/-   ##
=========================================
  Coverage     53.05%   53.05%           
  Complexity    22764    22764           
=========================================
  Files          1404     1404           
  Lines         88109    88109           
  Branches       1327     1327           
=========================================
  Hits          46748    46748           
  Misses        41361    41361

Impacted Files	Coverage Δ	Complexity Δ
lib/private/Share20/Manager.php	88.63% <ø> (ø)	229 <0> (ø)	⬇️
apps/files_external/lib/Lib/Storage/SMB.php	50.94% <0%> (-0.38%)	116% <0%> (ø)
apps/files_trashbin/lib/Expiration.php	91.93% <0%> (+1.61%)	29% <0%> (ø)	⬇️