Add Runtime API Endpoint Command Line Arg to Runtime Support

[philasmar]

Issue #, if available:

Description of changes:

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[normj]

I assume the Lambd1 project is just there for demonstration purposes as a draft PR.

[normj]

Be sure to add documentation that this should only be set for testing environments. Not when deployed to Lambda.

[normj]

Probably personal preference but I find this logic a bit confusing especially keeping state outside of the loop and waiting for value to get resolved next iteration of the look. What about this something like this which is untested.

private static LambdaBootstrapOptions ParseCommandLineArguments(string[] args)
{
    var option = new LambdaBootstrapOptions();

    if (args.Length > 1)
    {
        var arguments = new Dictionary<string, string>();
        for (int i = 1; i < args.Length; i++)
        {
            if (!string.IsNullOrEmpty(args[i]))
                throw new Exception();

            string key = args[i];
            int valuePos = i + 1;
            string value = null;
            if (args.Length < valuePos && !args[valuePos].StartsWith("-"))                
            {
                value = args[valuePos];
                i++;
            }

            arguments[key] = value;
        }

        if (arguments.TryGetValue("--runtime-api-endpoint", out var argument))
            option.RuntimeApiEndpoint = argument;

    }

    return option;
}