[feat][improvement][docs] implement FirewallRule CRD and support in firewall controller, remove finalizers on AddressSets

[AshleyDumaine]

What this PR does / why we need it: Adds a new CRD that can be reused to construct LinodeFirewalls in case rules are common between firewalls (e.g. common rules for control plane and worker node Firewalls)

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

Special notes for your reviewer:

TODOs:

• squashed commits
• includes documentation
• adds unit tests
• adds or updates e2e tests

Example using AddressSets and FirewallRules:

apiVersion: infrastructure.cluster.x-k8s.io/v1alpha2
kind: LinodeFirewall
metadata:
  name: sample-fw
spec:
  enabled: true
  inboundPolicy: DROP
  inboundRules:
    - action: ACCEPT
      label: inbound-api-server
      ports: "6443"
      protocol: TCP
      addresses:
        ipv4:
          - "192.168.255.0/24"
    - action: ACCEPT
      label: intra-cluster
      ports: "1-65535"
      protocol: "TCP"
      addressSetRefs:  # Can be used together with .addresses if desired.
        - name: vpc-addrset
          kind: AddressSet
  inboundRuleRefs:  # Can be used together with .inboundRules if desired
    - name: example-fwrule-udp
      kind: FirewallRule
    - name: example-fwrule-icmp
      kind: FirewallRule
  # outboundRules: []
  # outboundRuleRefs: []
  # outboundPolicy: ACCEPT
---
apiVersion: infrastructure.cluster.x-k8s.io/v1alpha2
kind: AddressSet
metadata:
  name: vpc-addrset
spec:
  ipv4:
    - "10.0.0.0/8"
---
apiVersion: infrastructure.cluster.x-k8s.io/v1alpha2
kind: FirewallRule
metadata:
  name: example-fwrule-udp
spec:
  action: ACCEPT
  label: intra-cluster-udp
  ports: "1-65535"
  protocol: "UDP"
  addresses:
    ipv4:
      - "10.0.0.0/8"
---
apiVersion: infrastructure.cluster.x-k8s.io/v1alpha2
kind: FirewallRule
metadata:
  name: example-fwrule-icmp
spec:
  action: ACCEPT
  label: intra-cluster-icmp
  protocol: "ICMP"
  addressSetRefs:  # Can be used together with .addresses if desired.
    - name: vpc-addrset
      kind: AddressSet

[cbang-akamai]

Put the finalizers back in 😤

[AshleyDumaine]

Put the finalizers back in 😤

[cbang-akamai]

Put the finalizers back in 😤