refactor(nix-compat/wire/bytes/reader): move size reading to async ctor HEAD r/8034 canon

with_size only existed to allow separating the phases of reading size
and reading data, and similarly the Size state only existed to allow
folding size reading into poll_read.

Neither of these are necessary if we make the constructor async,
and handle the size reading there.

As a bonus, this makes BytesReader::len sensibly typed, and permits
implementing is_empty, as Clippy demands of us.

Change-Id: I72173ec06d60b7998d16a3ecfc5e6ac5424bbed3
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11542
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>

0 files changed, 0 insertions, 0 deletions