revlog: overwrite revlog config through copy of the config object The new objects allow for this kind of blanket approach that make things cleaner. If we have more cases, it would probably deserve a context manager, but since we only have two usage, I don't think it is worth it.

revlog: move configuration attribute into dedicated object First this make things clearer as the number of configuration attributes has grown out of control, so gathering them make things clearer. Second, this will make future sharing them at different level simpler. Third it will allow us to make initialisation and temporary override simpler soon.

manifestrevlog: flag some inconsistency in bundle/union repo inheritance This "work" but still, this is weird, let us point it out.

randomaccessfile: drop explicit passing of file description The goal of this object is to manage IO, we still have to open the file if necessary, but this is all internal now.

revlog: drop more file description passing between private function They are no longer used as we are covered by the `reading` context

revlog: use a `reading` context in `_enforceinlinesize` We are about to enforce reading context on various operation, so we make sure top level method are in the right context. In the future we might move the responsibility of opening the revlog for reading higher in the call chain but lets limit the disruption for now.

revlog: drop the df argument to `sidedata` The intend of this argument is better filled by the `revlog.reading` or `revlog._writing` context. So we drop it to leave rooms for further cleanup and improvements.

revlog: drop the df argument to `rawdata` The intend of this argument is better filled by the `revlog.reading` or `revlog._writing` context. So we drop it to leave rooms for further cleanup and improvements.