Fix file public link permissions if public upload is not enabled

[julien-nc]

When "Administration -> Share -> Public upload" admin setting is disabled:

• We refuse to
  • create a share with update permissions
  • add update permissions to an existing share
• We remove PERMISSION_CREATE and PERMISSION_UPDATE when getting the share permissions

It makes perfect sense when sharing a directory but not when sharing a file which can then only be accessed in read-only by Text, NC Office and OnlyOffice.

If this is the intended behaviour, we should at least make it very explicit in the admin settings.

[blizzz]

milestone was wrong, master is 25.

[PVince81]

👍

[PVince81]

/rebase

[artonge]

PHPUnit failure:

1. Test\Share20\ManagerTest::testLinkCreateChecksNoPublicUpload
   Failed asserting that exception message '' contains 'Public upload is not allowed'.

[julien-nc]

PHPUnit failure:

1. Test\Share20\ManagerTest::testLinkCreateChecksNoPublicUpload
   Failed asserting that exception message '' contains 'Public upload is not allowed'.

@artonge I duplicated this test to check this works with files and fails with folders.

I also fixed the 3 other failing tests for which the share was just missing a target user and a Node. This is independent from the changes in this PR.

[juliusknorr]

Failure unrelated

[juliusknorr]

/backport to stable24