afform - Get default field <label> from label instead of title

[totten]

Overview

This updates afform/core and afform/gui to use better default labels -- e.g. when you add the gender_id field, it should default to "Gender" (label) instead of "Gender ID" (title).

Before

• In previous release. <Entity>.getFields returned a title. The title describes a field somewhat abstractly (e.g. gender_id has the title Gender ID).
• In the Afform UI, this title was used as the default.
• In the Afform GUI+HTML, you could optionally override the title.

After

• In current releases, <Entity>.getfields returns both a title and label. The label is simpler / more end-user-y string (e.g. Gender vs Gender ID).
• In the Afform UI, this label was used as the default.
• In the Afform GUI+HTML, you could optionally override the label.

Comments

This is technically a breaking-change for anyone who has overridden the default title - they would have to re-enter it as a label override. Ideally, this would be transitioned for compatibility -- but we don't have the validation/migration mechanism yet. There's a reasonable argument that it's not important to have a migration for this field at the current stage of development. More discussion on Mattermost: https://chat.civicrm.org/civicrm/pl/btbh1n88tp88zx39ean8gtgjke

Note that the PR adds an item about the BC break to the auditor backlog, which has a list of things that should be included in validation/migration.

CC @colemanw @eileenmcnaughton

[civibot]

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[colemanw]

@totten test failures relate

[totten]

@colemanw Thanks, yup. Updated test to match schema change. Squashed/rebased.