ci: More Nx Cloud features (#6906)

* adding root level checks to agent execution

* making root level scripts cacheable

* correctly setting inputs

* adding agents to ci.yml

* adding dynamic changesets to fix variable size PRs

* fixing resource name in dynamic-changesets.yaml

* reruning tests

* Delete tsbuildinfo file

* Update PR and CI scripts

* Add stop-agents-on-failure=false

* parallel=3

* Ignore .pnpm-store

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