Useful to better test business flows & replace yaml test files:
instantiating records & calling onchanges by hand is very
error-prone (it's easy to miss onchanges, or to manually set fields
which can't be set through the view we're interested in, ...)
odoo.tests.common.Form implements the basic *creation*
flow (fields_get, default_get, onchange) up to saving the record,
including proper handling of the required and readonly modifiers &
their domains.
* edition of existing records, including filtering out unmodified
fields when saving
* possibly buttons
* ensuring the API is convenient
