This commit adds support for a BrokenTcp provider that can make
connection attempts fail or time out.  It doesn't yet have a way to
turn on the failure.

arti-bench: support multiple streams per circuit, multiple circuits per sample.

Closes #380

See merge request tpo/core/arti!384

Add config paths table in arti docs

See merge request tpo/core/arti!386

fix reproducible build summary giving invalid branch and commit id

Closes #378

See merge request tpo/core/arti!383

Errors for dirprovider

Closes #370

See merge request tpo/core/arti!385

fix #378
also fix unrelated error in nightly rustdoc CI

Replace many manual trait impls with use of educe

See merge request tpo/core/arti!375

Speed up RsaIdentity decoding

Closes #377

See merge request tpo/core/arti!381

The doc include rune does not work with our MSRV; it needs 1.54.

The alternative would be some kind of cfg() but that would
  - not provide the crate-level doc on Rust 1.53
  - involve the use of cfg_attr

Instead, just do it the old way.

Previously we tried to do each connection in a run, and only then did we
start transferring data over them.  Now we collect a bunch of the
futures that return an open stream, and run them all in parallel
with using them.  This change includes connect-time in our
benchmarks, and allows us to test contention in our connect code.

Instead of using a Stream, I've changed the connection-generation
code to call a future-returning function directly, so we have a way
to explicitly pass which run we're in.

arti-testing: Initial implementation

See merge request tpo/core/arti!378

docker_reproducible_build: Bump to Rust 1.59

Closes #376

See merge request tpo/core/arti!380

The Rust upgrade is necessary since our Cargo.lock file now requires
`ed25519` 1.4.0, which requires edition2021, which requires Rust
1.56 or later.

The Alpine upgrade is opportunistic: we might as well.

I've also added comments to remind us to keep the .gitlab-ci.yml
and docker_reproducible_build files in sync, since my first version
of this commit messed that up.

Closes #376.

These aren't critical-path, but they do make the code a little nicer.

This commit changes the main parsing code for RsaIdentity in
tor-netdoc, and .

Previously, parse_hex_ident was something like 10% of our startup
CPU time; now it's only like ~2%.  (Still not perfect, but way
better.)

Closes #377.

We perform this operation in a bunch of places, and most of them
use hex::decode().  That's not great, since hex::decode() has to do
heap allocation.  This implementation uses hex::decode_to_slice(),
which should be faster.

(In the future we might choose to use one of the faster hex
implementations, but I'm hoping that this change will be sufficient
to get hex decoding out of our profiles.)

Part of #377.

Now the diff from the merge base does not contain any hits for ^\+.*bytes

Code motion and the minimal mechanical changes.

As per
  tpo/core/arti!375 (comment 2783078)

Empty crate right now

Tidy up many open-coded trait impls

See merge request tpo/core/arti!374

As per
  tpo/core/arti!375 (comment 2783080)

This is going to move to a new crate, but doing this now makes
things slightly clearer for me.

arti-client: Make dirmgr() and circmgr() return &Arc<..>

Closes #369

See merge request tpo/core/arti!379

Previously they returned an Arc, which wasn't necessary unless the
client actually _wanted_ a new Arc.

This would be an API break, except that these functions are marked
'experimental-api', so semver does not apply; nonetheless I've noted
the break in semver_status.md, just in case we care.

Closes #369

This commit adds a new program to try to implement the ideas behind
experimentation in arti#329.  In particular, it tries to implement
basic client "can I bootstrap and connect" functionality testing,
with a lot of instrumentation, and support for breaking things.

So far, the instrumentation is limited to counting TCP bytes and
connections, and counting events.  Still, this is enough to measure
behavior on some of the incorrect-clock tests.

NOTE:

For now, you are _required_ to pass in an explicit configuration, in
hopes that this will lead you to override your storage directories
for doing specific experiments.

Switch to shellexpand-fork version of shellexpand

See merge request tpo/core/arti!373