BUG - Don't allow dots in schema/field names

[blabadi]

Dots should not be allowed in schema names or field names.

Description

we use the dot internally to combine schema name and field name, having dots in any of those two names, will make splitting based on dot impossible.
see the diff endpoint on how the response is combined [schema_name.field_name]

Expected Behaviour

Users should not be allowed to use dots, and receive validation error if they attempt that

Actual Behaviour

Dots are accepted

[joneubank]

Functionality is now in place, needs test cases added.