Add experimental source-location dump argument

[bkhouri]

Add the experimental --experimental-dump-arguments-source-location option. When present, the parser fully parses the command line and then prints every parsed argument together with its value and source location (file:line for response-file args, argv[N] for command-line args), organized as a subcommand tree. Accepts =text (default) or =json.

Fixes #846
Relates to #41

Depends on #909

Checklist

• I've added at least one test that validates that my change is working, if appropriate
• I've followed the code style of the rest of the project
• I've read the Contribution Guidelines
• I've updated the documentation if necessary