streamclone: new server config and some API changes for narrow stream clones This patch introduces a new server config `experimental.server.stream-narrow-clones` which if set to True will advertise that the server supports narrow stream clones. This patch also pass on the includes and excludes from getbundle command to streamclone generation code. There is a test added to show that the includepats and excludepats are correctly passed. Upcoming patches will implement storage layer filtering for streamclones and then we can remove the temporary error and plug in the whole logic together to make narrow stream clones working. Differential Revision: https://phab.mercurial-scm.org/D5137