Fix broken link introduced by #1138 and add a link to Coding conventions.

Change Kani's compiler and tests to adapt to changes done to the toolchain. The biggest changes were:

Implement overflow checks as part of rvalue.rs instead of intrinsics due to lowering of intrinsics to BinOp.
Add a unsupported check for handling C string literals.


Co-authored-by: Adrian Palacios <73246657+adpaco-aws@users.noreply.github.com>

This removes dependency on atty, and tracing-tree (which depends on atty). This is in response to this security advisory:

https://rustsec.org/advisories/RUSTSEC-2021-0145

atty is removed by switching to std::io::IsTerminal. tracing-tree is removed by replacing HierarchicalLayer with a regular tracing_subscriber::fmt::layer that directs to stderr.

The PR also updates hermit-abi to 0.3.2 from 0.3.1, in response to 0.3.1 being yanked.

This PR resolves #2580.

Update Rust toolchain from nightly-2023-06-20 to nightly-2023-06-21 without any other source changes.

Co-authored-by: celinval <celinval@users.noreply.github.com>

This adds an executor (scheduler for async futures) to the Kani library, thus supporting `kani::spawn` as a replacement for `tokio::spawn`.

It also includes `kani::yield_now` which is similar to `tokio::yield_now`.

Co-authored-by: Celina G. Val <celinval@amazon.com>

Update toolchain and remove dependency on line number since we match exact value only, this generate a lot of noise whenever we update the toolchain.

…ld scripts (#2297)

We now pass `--cfg=kani` to build scripts, which allow users to use constructs such as `if cfg!(kani)` to conditionally compile their build scripts.

The build script may have logic that is not redundant to Kani, or even unsupported. Users can now change how their build works based on conditional compilation.

Co-authored-by: Kareem Khazem <karkhaz@amazon.com>

Update Rust toolchain from nightly-2023-06-22 to nightly-2023-06-23 without any other source changes.

This commit makes benchcomp delete fresh copies of benchmark directories after running the benchmark suite, by default. This is to save disk space, especially on CI machines which do not have enough disk space to run the perf suite. The new behavior can be turned off with the new --no-cleanup-run-dirs flag.

Co-authored-by: celinval <celinval@users.noreply.github.com>

Signed-off-by: Felipe R. Monteiro <felisous@amazon.com>