Add GraphQL mutation to create meetings via API

Add GraphQL mutation to create meetings via API: a task in bird-critic-1.5-full-300 (Harbor dataset). The decidim-meetings module gains a CreateMeetingType GraphQL mutation class under Decidim::Meetings . This allows API clients to create meetings programmatically, mirroring the participant-facing…

The task

The `decidim-meetings` module gains a `CreateMeetingType` GraphQL mutation class under `Decidim::Meetings`. This allows API clients to create meetings programmatically, mirroring the participant-facing creation form. The mutation requires that `creation_enabled_for_participants` is `true` on the component; it…

Part of kochsnow/bird-critic-1.5-full-300.