[Bug]: Calling platform build name --help starts a build about edk2-pytool-extensions

[Javagedes]

Thanks for bringing this to my attention. This is because there are two rounds of parsers. The first round is to find the build module use it to gather it's command line arguments. The second round of parsing is to parse for those command line arguments and then execute.

In the situation where the build module is provided, the first round of parsing consumes the --help argument, so when the second round of parsing occurs, the help flag does not exist and print help is not triggered.

PR #714 adds back in the "--help" flag to sys.argv if it was detected in the first round of parsing.