Basic ParamSpec Concatenate and literal support (#11847)
This PR adds a new Parameters proper type to represent ParamSpec parameters
(more about this in the PR), along with supporting the Concatenate operator.
Closes #11833
Closes #12276
Closes #12257
Refs #8645
External ref python/typeshed#4827
Co-authored-by: Shantanu <12621235+hauntsaninja@users.noreply.github.com>
Co-authored-by: Marc Mueller <30130371+cdce8p@users.noreply.github.com>
