Enhance ValidationUtils for load profile

[danielfeismann]

resolves #1357

[staudtMarius]

@danielfeismann I see one big problem with this validation. If we want to support custom load profiles, we have to either remove this validation later or adpat it, so that no exception is thrown.

[danielfeismann]

Which custom load profiles do you think of?

[staudtMarius]

Custom might not be the best name for it. I though, that someone might want to provide and use a load profile time series, that is not linked to a load profile, that is defined in the PSDM.

[danielfeismann]

Ok, my understanding of the docs is that one should use LoadProfile#NO_LOAD_PROFILE for this purpose.

[staudtMarius]

If you use for example primary data, you can add LoadProfile#NO_LOAD_PROFILE. But if we want to use the load profile service, we need to specify a profile in the load input.

[danielfeismann]

Ok.

(a) If I understand correctly, all inputs of load_profile will be ignored when primary data is used as the load profile. If so, LoadProfile#NO_LOAD_PROFILE would no longer be used and could perhaps be removed.

(b) I'm not sure if I can think of a case where someone would introduce their own load profile and not use the primary data method. So, in my humble opinion, I would prefer a bit more safety than flexibility. But I'm open to other suggestions.

[staudtMarius]

One safe way, that allows some flexibility, would be to use the method LoadProfile.parse. This method loads all available profiles and then checks, if the provided string can be parsed as a load profile.