Enhance emission entries with id fields

[codingfabi]

All of the emission entries should contain a unique identifier and the id of the user that created the entry. This would enable us to select/delete/edit specific entries.

Is a blocker for #248 and #97

[codingfabi]

@redfrexx I did not really make progress here because I do not understand how to reset the database schema and how to add a uuid field to the emission entries. Maybe you can show me an example for one of the entry types or smth...

[redfrexx]

Adding an id field should work using the models.UUID() class, e.g. https://github.com/pledge4future/WePledge/blob/dev/backend/src/emissions/models/customUser.py#L14C1-L14C1

After changing the database schema you have to delete all docker containers, images and volumes and delete all files in the migrations folder. Hope this helps, @codingfabi!