Move entity model to entity folder in Angular

[kaidohallik]

After #13125 (comment) decided to resolve also point 1 in #13125 - this PR resolves that.

Enumerations: initial plan was to move shared/model/enumerations/ to model/ but after thinking came to the conclusion that entities/enumerations/ is better place and moved there:

• avoids creating new subfolder to root folder
• enumerations are coming with entities, so entities folder is the best fit for their location

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