Enabling configuring IP Address for Dotnet Backend

[Niharikadutta]

This PR gives the user the ability to specify a particular IP address they want the Dotnet backend process to spin up on while submitting the .NET for Apache Spark application.

The user can do that by setting the following environment variables:

1. For the IP address they want to spin DotnetBackend on - DOTNET_SPARK_BACKEND_IP_ADDRESS
2. For the IP address they want to run the .NET for Spark Application on - DOTNET_SPARK_CALLBACK_SERVER_IP_ADDRESS

This PR fixes #419

[imback82]

<dotnet backend IP address> // if not added, default islocalhost`

Can we not update the usage, but let the user set the environment variable?

[imback82]

@suhsteve Can you help reviewing this PR?

[laskli]

@Niharikadutta Any updates on this one? We are having trouble debugging our .Net for Spark application with docker container setup and this seems to fix the issue.

[Macromullet]

Can we get an update on this PR @Niharikadutta? What are the security concerns @imback82 ? If it's user-configurable and defaults to the most secure, how is that any different than an ASP.NET server allowing 0.0.0.0 when specified explicitly by the user. The general guidance for WSL2 is to run Linux based things you want to connect to with 0.0.0.0. We wouldn't be doing the override in anything other than a debug/test scenario, so it would be secure by default.

[Niharikadutta]

@Macromullet , @ZavezX we are working on getting this PR merged asap, thank you for your patience.

[Niharikadutta]

@suhsteve, @elvaliuliuliu Could you please help review?