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

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