insights: add option to create insight mutation to add to dashboard
Created by: coury-clark
Closes https://github.com/sourcegraph/sourcegraph/issues/26452
Adds an argument to the GraphQL create insight mutation to optionally specify dashboards to attach at creation time.
This also includes a few small refactors to fix the DashboardStore transaction sharing mechanism, and a change to the HasDashboardPermissions args.
Missing permissions for a dashboard:
Before adding the insight here is the dashboard: