fix: #3628977 [regression] Show flags on custom form mode edit forms

Chris Greenrequested to merge
issue/flag-3628977:3628977-regression-revert-3a355372 into 5.1.x

Since #3169627 the isAddEditForm() check runs, and it only accepts the 'default' and 'edit' operations. Forms rendered with a custom form mode (e.g. Form Mode Manager) use the form mode ID as the operation, so flags were no longer shown on them.

Treat operations that match a form mode of the flaggable entity type as add/edit forms. Operations that are not form modes, such as Scheduled Transitions forms, remain excluded.

Co-Authored-By: Claude Opus 5.5 noreply@anthropic.com

Related to #3628977

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