pull: merge bookmark updates and imports We do all the things in one go now, updating existing bookmark, adding new ones, and overwriting the ones explicitly specified for --bookmark. This impacts the tests by removing some duplicated or unnecessary output.

pull: gather explicit bookmark pulls with bookmark updates There is no reason to make them at different times. So we gather them. This is the first step toward merging them.

subrepo: stop pulling bookmark manually Bookmark pulling is now done with all the other pull steps in the `exchange.pull` function.

pull: retrieve bookmarks through bundle2 We can retrieve any pushkey namespace through bundle2. So we also ask for bookmark data and use them to update the local repo.

pull: retrieve bookmarks before obsmarkers Retrieving bookmarks before obsmarkers will avoid turning some changesets hidden right before making them visible again if a bookmark keeps them visible.

pull: move bookmark pulling into its own function This requires adding an attribute on the pulloperation object. The bookmark pulling is protected behind a "todostep" as other steps of pull.

pull: perform the todostep inside functions handling old way of pulling This matches what is done during push.

bookmark: remove now unused `pushtoremote` function Everything is unified in the push discovery now.

push: gather all bookmark decisions together The discovery phases for bookmarks now use the list of explicitly pushed bookmarks to do addition, removal and overwriting. Tests are impacted because this reduces the amount of listkeys calls issued, removes some duplicated messages and improves the accuracy of some messages.

push: prepare the issue of multiple kinds of messages To gather all the bookmark pushing actions together, we need code performing those actions to be ready for them. We need to be able to produce different messages for different actions.