ci: fix dependabot, commit & check Cargo.toml

[CarolYeh910]

Resolved issues:

resolves #4986

Description of changes:

Based on my experiment, simply excluding s2n-tls-sys from dependabot.yml cannot prevent dependabot retrieving the Cargo file. Hence we decided to commit s2n-tls-sys/Cargo.toml and add a new job in ci_rust.yml to check if the file is up-to-date. Furthermore, testing showed that generated feature list may have a different order from the committed Cargo.toml, thus I added a sort() to the source code generate/src/main.rs.

Below is a list of changed files:

1. Updated crate paths in dependabot.yml
2. Created a GitHub action in ci_rust.yml to check if s2n-tls-sys/Cargo.toml is up-to-date in future PRs
3. Updated extended/.gitignore and committed s2n-tls-sys/Cargo.toml
4. Added sorting to the unstable feature list generated by generate/src/main.rs

Call-outs:

None

Testing:

• Tested on my forked repository and two cargo runs both passed: cargo in - Update #954923362 and cargo in - Update #954930736
• The new CI job succeeded on this PR: https://github.com/aws/s2n-tls/actions/runs/13002032439/job/36262388644

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.