copy: migrate `opts` to native kwargs

config: use the writefile() utility to create the sample hgrc This function uses a context manager.

config: migrate `opts` to native kwargs

clone: migrate `opts` to native kwargs

bundle: migrate `opts` to native kwargs

branches: migrate `opts` to native kwargs

branch: migrate `opts` to native kwargs

bookmark: migrate `opts` to native kwargs There are a bunch of callers for `ui.formatter()`, so convert to bytes only for that call.

archive: migrate `opts` to native kwargs I'm not sure how to handle migrating core APIs like `scmutil.match`, so kick that can down the road. (Plus it's used all over, so the callers need to be migrated first.)

backout: migrate `opts` to native kwargs It will take a bit to unwind `cmdutil.commit`, so there's a conversion to byteskwargs there, without changing the type of `opts` in this function. That's also useful to flag it as needing to be changed.

cmdutil: migrate `opts` on commitstatus() to native kwargs

cat: avoid round tripping **opts -> byteskwargs -> strkwargs Some internal users still want byteskwargs, so they are serviced in place. Once this pattern of changing types is eliminated everywhere, the remaining internal uses can be cleaned up individually (hopefully).

branching: merge stable into default

transaction: actually delete file created during the transaction on rollback Transaction currently has two modes: - one where file created during the transaction are deleted on rollback, - one where file created during the transaction are truncated to 0 on rollback. Before this change, `hg rollback` and `hg recover` are using the "delete" mode and transaction abort is using the "truncate" option. This difference is never really explained. A long time ago, there was two code paths, with this divergence existing for unclear reasons. When the two code paths got merged into a single one, a boolean argument have been added to preserve this divergence, mostly probably as a cargo cult. The divergence is weird and induce bad surprises, and the truncate behavior is a bit odds, introducing other bad surprises (e.g. 08ecbdba186f) So solve this, we stop using the "truncate" behavior and unify on the "delete" behavior. Despite being currently more "common", the truncate behavior seems less natural, resulting in the transaction leaving empty file around. This is landed on default, early in the cycle, to help us catch problems that could emerge.

rhg: tweak rhg fallback code structure The goal here is to share the code that accesses the config setting, but also move it to the top-level, so that we can more easily change this code later. (in fact in Jane Street we want to make it choose chg in some cases)