Correct handling of arguments that take values.

[freakboy3742]

Python 3.12.7 modified the handling of command line arguments in a way that broke Briefcase's handling of arguments that take values (e.g., -C <config=value>, -d <device>, etc).

Briefcase's command line handling is based on pushing argparse to its limits, performing partial parsing of arguments before all options have been registered. This is needed to allow commands to register their own arguments, and for the help for commands to be responsive to the target platform and output format.

The parser also has 2 optional positional arguments for most commands (platform and output_format). Because they're optional, there's an ambiguity between these positional arguments, and arguments with flags that take values that haven't been registered yet.

This PR takes a quick-and-dirty approach, removing any argument that looks like it might be passing a value from consideration from the partial parse. It's not pretty, but it works.

Fixes #2026.

PR Checklist:

• All new features have been tested
• All new features have been documented
• I have read the CONTRIBUTING.md file
• I will abide by the code of conduct

[freakboy3742]

Superseded by #2028, which fixes the underlying problem with parsing rather than trying to work around it.