RKE2 Template: Nodepools and other arrays not showing in UI

[slickwarren]

(spoke with Daishan about this offline -- known limitation of UI until further logic is implemented) currently, there is no way to add multiple nodepools through the UI in RKE2 cluster templates

This is an issue for other array types as well, such as agentEnvVars.

workaround: user can add arrays to the yaml via the edit as yaml button. i.e.

nodepools:
- name: pool-1
  quantity: 1
  etcd: true
  worker: true
  controlplane: true
  image: ubuntu-20-04-x64
  backups: false
  ipv6: false
  monitoring: false
  privateNetworking: false
  region: sfo3
  size: s-4vcpu-8gb
  userdata: null
  sshPort: 22
  sshUser: root
- name: pool-2
  quantity: 1
  etcd: false
  worker: true
  controlplane: false
  image: ubuntu-20-04-x64
  backups: false
  ipv6: false
  monitoring: false
  privateNetworking: false
  region: sfo3
  size: s-4vcpu-8gb
  userdata: null
  sshPort: 22
  sshUser: root

**Repro Steps:**
on master-head (6b430f3)
* deploy RKE2 templates by adding a repo with cluster templates
* go to deploy a cluster via the template
* go to nodepools in the UI
-> no option to add more than 1 nodepool

parent ticket: https://github.com/rancher/dashboard/issues/2972

[lindhe]

Related to https://github.com/rancher/dashboard/issues/5754