Supports custom configuration of cluster dns

[pixiake]

What type of PR is this?

/kind feature

What this PR does / why we need it:

Supports custom configuration of cluster dns, including coredns and nodelocaldns.
example：

  dns:
    dnsEtcHosts: |
      192.168.0.100 api.example.com
      192.168.0.200 ingress.example.com
    coredns:
      additionalConfigs: |
        whoami
        log
      externalZones:
      - zones:
        - example.com
        - example.io:1053
        nameservers:
        - 1.1.1.1
        - 2.2.2.2
        cache: 5
      - zones:
        - mycompany.local:4453
        nameservers:
        - 192.168.0.53
        cache: 10
      - zones:
        - mydomain.tld
        nameservers:
        - 10.233.0.3
        cache: 5
        rewrite:
        - name substring website.tld website.namespace.svc.cluster.local
      rewriteBlock: |
        rewrite stop {
          name regex (.*)\.my\.domain {1}.svc.cluster.local
          answer name (.*)\.svc\.cluster\.local {1}.my.domain
        }
      upstreamDNSServers:
      - 8.8.8.8
      - 1.2.4.8
      - 114.114.114.114
    nodelocaldns:
      externalZones:
      - zones:
        - example.com
        - example.io:1053
        nameservers:
        - 1.1.1.1
        - 2.2.2.2
        cache: 5
      - zones:
        - mycompany.local:4453
        nameservers:
        - 192.168.0.53
        cache: 10
      - zones:
        - mydomain.tld
        nameservers:
        - 10.233.0.3
        cache: 5
        rewrite:
        - name substring website.tld website.namespace.svc.cluster.local

Which issue(s) this PR fixes:

Fixes #

Special notes for reviewers:

Does this PR introduced a user-facing change?

Additional documentation, usage docs, etc.:

[ks-ci-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: pixiake

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[redscholar]

/lgtm

[ks-ci-bot]

LGTM label has been added.

Git tree hash: ad5fe96964c2dc86caf1c6d3a0b747bb0edb47d8