rez-pip should cleanly fail if resolving a python package fails

[JeanChristopheMorinPerso]

See https://academysoftwarefdn.slack.com/archives/C0321B828FM/p1697125828936919?thread_ts=1697123068.952239&cid=C0321B828FM.

Seems my issue is that I had an issue that caused Rez to be able to find a "pip" package, but when performing the resolve, it broke. There doesn't appear to be any sort of check in the code to confirm that the ResolvedContext.status == ResolverStatus.solved

This applies to the original rez-pip, but it also applies to us.

I don't know in which case a solve would fail for such simple requests, but we should support failures just in case. See

rez-pip/src/rez_pip/rez.py

Lines 246 to 262 in 9c61a5d

	for package in packages:
	resolvedContext = rez.resolved_context.ResolvedContext(
	[f"{package.name}=={package.version}"]
	)
	# Make sure that system PATH doens't interfere with the "which" method.
	resolvedContext.append_sys_path = False
	for trimmedVersion in map(package.version.trim, [2, 1, 0]):
	path = resolvedContext.which(f"python{trimmedVersion}", parent_environ={})
	if path:
	pythons[str(package.version)] = pathlib.Path(path)
	break
	else:
	_LOG.warning(
	f"Failed to find a Python executable in the {package.qualified_name!r} rez package"
	)

.