Log devproxy activity file contents in post step and support custom log file name

[garrytrinder]

Currently, Dev Proxy activity is logged to a devproxy.log file. To improve debugging, the post step should automatically output the contents of this log file after execution. Additionally, the update should allow users to specify a custom log file name, which can be passed to the setup or start action. This flexibility will help users manage logs more effectively for different environments and use cases.

Acceptance Criteria:

• In the post step, output the contents of the log file used during execution.
• Support configuration of a custom log file name via parameters to the setup or start action.
• Ensure the feature works regardless of the log file name chosen.
• Update documentation/examples to show usage with custom log file names.