CLI based updater

[MorrisJobke]

• add more test cases
• add message that after the "code update" the user needs to call ./occ upgrade (or call it directly afterwards from within the console command - problem here is regarding properly forwarding the output of the called script async)

How to test

• download the phar from https://github.com/nextcloud/updater/releases/tag/0.1
• place it in updater/
• set the executable bit for the phar
• call it from within the updater/ folder: ./updater.phar

How does it look

[MorrisJobke]

This is ready for reviewing @nickvergessen @rullzer @LukasReschke

Use phar in https://github.com/nextcloud/updater/releases/tag/0.1 to actually test it ;)

[rullzer]

Test fail.
Tried a few updates locally and it worked like a charm!

I'll try to have a bit deeper look into the code now.

[rullzer]

maybe add

    "config": {
       "optimize-autoloader": true,
       "classmap-authoritative": true
     },

For more secure autoloader? That way it will only look trough it lists of known files (so the created list of the dumpautoloader command). Which means no loading magic and accidentially loading a wrong file.

[rullzer]

We need more testers but in general yes. Lets do this 👍

[MorrisJobke]

Version 1.0 is build: https://github.com/nextcloud/updater/releases/tag/1.0

[MorrisJobke]

CI says 🚀