[internal/common/testutil] Add support for testing listening udp ports

[jspaleta]

Description:
Refactored the internal testutil functions for available port discovery used in component service mocking to be able to support udp ports similarly to existing tcp port functionality. Once this is merged, this should provide a path forward to fixing racy tests for all UDP listening components (ex: statsd and carbon receivers), where the tests are currently marked to be skipped.

Summary of changes:

• Extended the internal testutil functions to make it possible to mock listening UDP ports for components that make use of udp listening servers (ex: statsd receiver).

• The existing findAvailableAddress function was refactored to support both net.Listen and net.ListenPacket supported network types. net.ListenPacket is needed for udp available port discovery.

• A new testutil function GetAvailableLocalNetworkAddress was added that exposes the network string argument needed for net.Listen and net.ListenPacket used in findAvailableAddress.

• The existing GetAvailableLocalAddress function is refactored as a wrapper around GetAvailableLocalNetworkAddress to provide backwards compatible behavior for all existing functional mock tcp listening test.

Ref Issue:
#10916

Link to tracking Issue:

Testing:
Added new test for finding free UDP listening port.

Documentation:
No additional documentation added.

[djaglowski]

Thanks for the contribution @jspaleta!