ci: Introduce Nx agents (#6863)

* introducing nx agents

* busting cache to get some test runs in

* fixing distribut option

* fixing yml syntax error

* bumping up agent count

* experimenting with parallel and agent count

* kick tires

* rm stuff to break cache

* reordering setup to start agents earlier

* adding in nvmrc file

* making sure pnpm is there for node setup

* kick tires

* Move parallel flag into workflow

---------

Co-authored-by: Lachlan Collins <1667261+lachlancollins@users.noreply.github.com>