Add Hound/Rubocop config; Make Ruby style consistent

**Analog to opf/openproject#1879 and opf/openproject#2136**
Line is too long. [107/80]<br>Avoid using `rescue` in its modifier form.<br>Do not use semicolons to terminate expressions.<br>Prefer double-quoted strings unless you need single quotes to avoid extra backslashes for escaping.