Unlock folder without token leads to 404

[tobiasKaminsky]

• have an encrypted folder
• DELETE lock without passing token as header
  --> returns 404

Instead it should give a better error message

[artonge]

Not authorised ?

[tobiasKaminsky]

No. According to API it needs token, which is okay.
But 404 is then misleading.
Better would be a 412 precondition failed, with info that token is missing.

[artonge]

First part server side:

• Add OCSPreconditionFailedException server#39164

[artonge]

Change done in #405