Tesha/azure firewall support dns proxy

[tejasshah7]

Description

These changes are to add support for DNS Proxy options to Azure Firewall command. 3 new parameters are added.

• DNSServers: Array of strings
• DNSEnableProxy: This can betrue/false with default being false

Allowed:
New-AzFirewall -Name "azFw" -ResourceGroupName $rgName -Location centralus -VirtualNetwork $vnet -PublicIpAddress $pip -DNSEnableProxy true -DNSServers @("10.10.10.1", "20.20.20.2")

Allowed only if no Network Rules have FQDNs:
New-AzFirewall -Name "azFw" -ResourceGroupName $rgName -Location centralus -VirtualNetwork $vnet -PublicIpAddress $pip -DNSRequireProxyForNetworkRules false

Only validation required is

• If DNSRequireProxyForNetworkRules is explicitly set to False with DNSProxy disabled too, then no Network Rules can have FQDNs. Default value is true

Checklist

• [x ] I have read the Submitting Changes section of CONTRIBUTING.md
• The title of the PR is clear and informative
• The appropriate ChangeLog.md file(s) has been updated:
  • For any service, the ChangeLog.md file can be found at src/{{SERVICE}}/{{SERVICE}}/ChangeLog.md
  • A snippet outlining the change(s) made in the PR should be written under the ## Upcoming Release header -- no new version header should be added
• The PR does not introduce breaking changes
• If applicable, the changes made in the PR have proper test coverage
• For public API changes to cmdlets:
  • a cmdlet design review was approved for the changes in this repository (Microsoft internal only)
  • the markdown help files have been regenerated using the commands listed here

[adxsdkps]

Can one of the admins verify this patch?

[tejasshah7]

Against master instead of network-april so closing this.