remotenames: add new namespaces for remotebookmarks and remotebranches This patch adds two new namespaces which will be enabled by remotenames extension. The namespaces are remotebookmarks and remotebranches. Adding them as namespaces will show them in various commands' output such as log, show work. This will also unable to access changesets using that name. Tests are also added for the same. This is a part of moving hgremotenames extension to core. hgremotenames: https://bitbucket.org/seanfarley/hgremotenames Differential Revision: https://phab.mercurial-scm.org/D1758