Replace usage of recently removed SocketUtils

[onobc]

Main fails to compile as SocketUtils has been deprecated->removed from the Spring Framework.

Temporary Workaround:

I took a very slimmed down version of org.springframework.util.SocketUtils and dropped it under spring-cloud-function-core. It only exposes the findAvailableTcpPort as that is all that the tests are using.

Suggested Alternative

Instead user port 0 and rely on the OS to assign a port to the server and then query the server for the port it is running on.

Options

Option 1: Replace all usages of SocketUtils w/ the suggested alternative.

Option 2: Create a TestSocketUtils and put in shared test lib

I have started a team discussion and will let that drive the chosen option. In the meantime I will replace as many usages as possible.

cc: @olegz

[onobc]

About 80% through the changes w/o the need for SocketUtils so far. I do see a couple of places I may need it though.

[chrylis]

Was the referenced possible TestSocketUtils ever created? I am relying on SocketUtils because the DynamoDB Local server does not support starting on a random port.

[onobc]

Hi @chrylis - it exists in the associated PR. However, the intention is to remove it ASAP in favor of a more centrally available one (such as the one in spring-cloud-test-support. Also, the one in the PR will not be published or usable outside of the SCF repo.