V4 Rust examples

[spencer-ritual]

Currently, the examples at /examples/rust are out of date and do not compile. They pull the latest version of icicle libs (v4), but the code expects the V3 API

[omershlo]

Good catch!
Cc: @LeonHibnik

[LeonHibnik]

@spencer-ritual Thanks for the catch! Feel free to try #1041