[dev.cmdgo] don't give command-line-arguments a module

Don't associate command-line-arguments with a module. Even though the
sources in the command-line-arguments package may exist within the
module's packages, the command-line-arguments package is distinct from
the package in the module. It has its own identity, and further, even if
all the same sources are listed, build tag filtering is not applied for
command-line-arguments.

For #45713

Change-Id: I555752021d58ea25e65699b4959f787ea5fa2cda
Reviewed-on: https://go-review.googlesource.com/c/go/+/339170


Trust: Michael Matloob <matloob@golang.org>
Trust: Bryan C. Mills <bcmills@google.com>
Run-TryBot: Michael Matloob <matloob@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>