chore(bindings): move tokio examples to dedicated folder

[jmayclin]

Resolved issues:

resolves #4909 , #4910 , #4911

Description of changes:

All of the rust-sec issues are for transitive dependencies of one of our dev dependencies, clap. This can be solved by upgrading clap to 4.0, but that breaks our MSRV.

So instead we are moving the examples out of the main s2n-tls-tokio crate, and we are moving it into the dedicated rust-examples folder. This required two things.

1. move rust-examples/client-hello-config-resolution/certs to rust-examples/certs. This allows all of the examples to use the same certs folder (or reuse certs)
2. move the s2n-tls-tokio example binaries to a dedicated tokio-server-client example.

Testing:

I manually ran the examples to confirm that they were functioning as expected.

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