Refactor examples to support subfolder execution

[lukehinds]

To keep things more tidy, each example is moved under its core function , for example rekor or cosign. A mapping is then made within Cargo.toml.

This will make the folders more easily browsable for users and will allow multiple file support. We can then use different file names beyond just main.rs

[[example]]
name = "foo"
path = "examples/cosign/verify/foo.rs"

cargo run --example foo

[[example]]
name = "bar"
path = "examples/cosign/verify/bar.rs"

cargo run --example bar

Signed-off-by: Luke Hinds [email protected]

Summary

Release Note

Documentation

[lukehinds]

https://github.com/sigstore/sigstore-rs/pull/112 will address CI failure