Fix sharing expiration date handling and saving

[skjnldsv]

Regression from #33915

Fix #34926

Explanations

• share.expireDate represent the Database expiration data. Which expects a YYYY-MM-DD format
• The native DatePicker require a javascript Date as value
• We need to make sure the data we sent is not UTC-aware.

  new Date('2020-01-01 00:00:00').toISOString()
  > '2019-12-31T23:00:00.000Z'

• The backend forces a time on the expiration field (for clients I'm assuming), so we also need to make sure to ignore this when parsing the data
  

  server/apps/files_sharing/lib/Controller/ShareAPIController.php

  Line 236 in 62919ac

  $result['expiration'] = $expiration->format('Y-m-d 00:00:00');

  server/apps/files_sharing/src/mixins/SharesMixin.js

  Lines 161 to 162 in e03248e

  	const regex = /([0-9]{4}-[0-9]{2}-[0-9]{2})/i
  	return new Date(date.match(regex)?.pop())

[skjnldsv]

/backport to stable25

[artonge]

Nitpicks but fine otherwise :)

[szaimen]

Works in my testing. However here we need to add date +1 since otherwise the default will not work as the current date is already reached.

server/apps/files_sharing/src/components/SharingEntryLink.vue

Line 428 in e03248e

defaultExpirationDate = new Date()

[skjnldsv]

Pushed and ready to go!

[szaimen]

Didnt test again but I trust you that it works now :)

[PVince81]

Tested, works 👍

[skjnldsv]

--- Failed scenarios:
512 |  
513 | /drone/src/tests/acceptance/features/app-files-sharing.feature:402

Doesn't seems related, also failed on previous merges to master
https://drone.nextcloud.com/nextcloud/server/25892/58/4