remotenames: add names argument to remotenames revset This patch adds names argument to the revsets provided by the remotenames extension. The revsets are remotenames(), remotebranches() and remotebookmarks(). names can be a single names, list of names or can be empty too which means it's an optional argument. If names is/are passed, changesets which have those remotenames will be returned. If names are not passed, changesets from all the remotenames are shown. Passing an invalid remotename does not throw error. The name argument also supports pattern matching. Tests are added for the argument in tests/test-logexchange.t Differential Revision: https://phab.mercurial-scm.org/D3639