A PexRequest should support pex -c.

[jsirois]

Right now, it only supports specifying modules or entry point functions:

pants/src/python/pants/backend/python/util_rules/pex.py

Lines 357 to 358 in c9d6826

	:param entry_point: The entry-point for the built Pex, equivalent to Pex's `-m` flag. If
	left off, the Pex will open up as a REPL.

pants/src/python/pants/backend/python/util_rules/pex.py

Lines 550 to 551 in c9d6826

	if request.entry_point is not None:
	argv.extend(["--entry-point", request.entry_point])

Of the three options for specifying a main this only allows for the worst two in terms of stability. Since Pants uses Pex to package python tools (i.e.: binaries folks run like pytest or black), it should probably bind to those public names which are console scripts instead of modules (slightly less stable presumably) or entry point functions (clearly the least stable). Pex supports this with -c.

[jsirois]

This seems especially important because we generally allow users to change versions of tool libraries. Most of the time thats coupled with the ability to change entry point functions but its not in a few cases. Regardless, binding to a console script should make this moot across tool versions since any tool author changing their console script names has broken their brand and their users. Highly unlikely esp vs. moving around code.