* hide: 'New Project board' button

* there is no reason to show the button for users that are not signed in

* update template: specifies the condition together with another one

as per lafriks' suggestion in the comment

* chore: add proper user authorization check

* chore: also hide button if repo is archived

* chore: show project board edit/delete menu to authorized users only

* chore: drop the redundant IsSigned check

* CanWriteIssues and CanWritePulls implies (and requires) signed in user

* Add CanWriteProjects and properly assert permissions

Signed-off-by: Andrew Thornton <art27@cantab.net>

Co-authored-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>