Support all valid vss paths

[rafaeling]

Databroker now accepts any path composed of any character except : and whitespace, i.e.

- Vehicle._kuksa.databroker.GitVersion
- Vehicle.Do_you_not_like_smörgåstårta
- Vehicle.tschö_mit_ö
- Vehicle.東京_Москва_r#true

[argerus]

These changes still include validation of paths "sprinkled" throughout the code.

As discussed and concluded in the corresponding issue (#674), a better approach would be to add validation only at the point of adding new entries (i.e. here).

[SebastianSchildt]

We should work on getting Vehicle._kuksa.databroker.GitVersion.Do_you_not_like_smörgåstårta.tschö_mit_ö.東京_Москва_r#true into the VSS standard catalogue :)