As a user I would like to override the behaviour of 'Create project' button click action.  For example, I should be able to pass a callback which would open a custom modal, or just create a project and any other needed resources without any interaction.

After team discussion the path forward is the extension enable the contents of the Create Project modal to be replaced. The ‘Name’ field will need to be supplied since it's required.

Acceptance criteria

• add extension point so plugin creators can provide their own callback, to override the create project form behaviour.
• update docs with this extension point.
• add a a custom modal to the demo plugin for testing. The modal will create a project and quota for that project.