sidedata: move to new sidedata storage in revlogv2
The current (experimental) sidedata system uses flagprocessors to signify the
presence and store/retrieve sidedata from the raw revlog data. This proved to be
quite fragile from an exchange perspective and a lot more complex than simply
having a dedicated space in the new revlog format.
This change does not handle exchange (ironically), so the test for amend - that
uses a bundle - is broken. This functionality is split into the next patches.
Differential Revision: https://phab.mercurial-scm.org/D9993
[tool.black]
line-length = 80
exclude = '''
build/
| wheelhouse/
| dist/
| packages/
| \.hg/
| \.mypy_cache/
| \.venv/
| mercurial/thirdparty/
'''
skip-string-normalization = true
quiet = true