Bump our clang toolchain to version 16

Summary: This includes clang-16 as a compiler, but also clang-format-16 and clang-tidy-16 as linters.

Test Plan:

arc lint --everything

Run the clang builds.

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Differential Revision: https://reviews.bitcoinabc.org/D17006