## Context
This PR introduces overrides for view fields which will be useful for
page layout FIELDS widgets fields position/groups/visibility override +
restore logic.
This PR prepares the refactor of record field definition and column
definition.
We need to separate the two concepts of FieldInput and FieldContext at
the cell level, and the new RecordField concept that will replace
FieldDefinition at the metadata and state level.
So we create a new ui sub-folder in the already existing record-field
folder, in order to separate those two concepts that are still very
close.
Weiko