Support declarative configuration to deploy cluster

[innobead]

Is your feature request related to a problem? Please describe.
The current way to deploy a cluster is using command options. There is no declarative way to do that.

Describe the solution you'd like
Have a new option of kubefire create to support deploy by a declarative configuration file. ex: kubefire create --config=<file>

[innobead]

➜  kubefire (master) ✗ cat cluster.yaml                                  
name: ""
bootstrapper: k3s
pubkey: /home/davidko/.kubefire/clusters/demo-k3s/key.pub
prikey: /home/davidko/.kubefire/clusters/demo-k3s/key
version: v1.18.8
image: ghcr.io/innobead/kubefire-opensuse-leap:15.2
kernel_image: ghcr.io/innobead/kubefire-ignite-kernel:4.19.125-amd64
kernel_args: console=ttyS0 reboot=k panic=1 pci=off ip=dhcp security=apparmor apparmor=1
extra_options:
  server_install_options:
    - --disable=metrics-server
deployed: false
master:
  count: 1
  memory: 2GB
  cpus: 2
  disk_size: 10GB
worker:
  count: 0
  memory: 2GB
  cpus: 2
  disk_size: 10GB

➜  kubefire (master) ✗ kubefire cluster create demo-k3s --config=cluster.yaml
... 

➜  kubefire (master) ✗ kubefire cluster config demo-k3s -o yaml
name: demo-k3s
bootstrapper: k3s
pubkey: /home/davidko/.kubefire/clusters/demo-k3s/key.pub
prikey: /home/davidko/.kubefire/clusters/demo-k3s/key
version: v1.18.8
image: ghcr.io/innobead/kubefire-opensuse-leap:15.2
kernel_image: ghcr.io/innobead/kubefire-ignite-kernel:4.19.125-amd64
kernel_args: console=ttyS0 reboot=k panic=1 pci=off ip=dhcp security=apparmor apparmor=1
extra_options:
  server_install_options:
  - --disable=metrics-server
deployed: true
master:
  count: 1
  memory: 2GB
  cpus: 2
  disk_size: 10GB
worker:
  count: 0
  memory: 2GB
  cpus: 2
  disk_size: 10GB

➜  kubefire (master) ✗ eval `kubefire cluster env demo-k3s`
➜  kubefire (master) ✗ kubectl get pods --all-namespaces            
NAMESPACE     NAME                                     READY   STATUS      RESTARTS   AGE
kube-system   local-path-provisioner-6d59f47c7-pzf5f   1/1     Running     0          43s
kube-system   helm-install-traefik-c4kfx               0/1     Completed   0          43s
kube-system   coredns-7944c66d8d-kq25v                 1/1     Running     0          43s
kube-system   svclb-traefik-62grx                      2/2     Running     0          24s
kube-system   traefik-758cd5fc85-mfwzl                 0/1     Running     0          24s