[Chronik] Install nightly rust toolchain dependency (as "abc-nightly")

Summary:
Install nightly-2022-06-29 in install-dependencies.sh

This allows us to use the unstable features of rustfmt, most importantly --skip-children, which gives us similar behavior to the other linters.

We name it "abc-nightly", and invoke it by adding +abc-nightly to commands.

Test Plan:

1. docker run -i -t bitcoinabc/bitcoin-abc-dev
2. Paste the lines in the diff
3. $RUST_HOME/rustc +abc-nightly --version outputs rustc 1.64.0-nightly (830880640 2022-06-28)

Reviewers: Fabien, #bitcoin_abc

Reviewed By: Fabien, #bitcoin_abc

Differential Revision: https://reviews.bitcoinabc.org/D11688