chore: convert package to library

[kkafar]

Description

Converted our crate to library format.

Linked issues

Resolves #30

Converting crate to a library also causes doctests to be auto run by cargo test ==> resolves #120

Important implementation details

• Moved examples to external package - it resides in our repo, but it shall not be shipped when packaging. We should consider using include / exclude in Cargo.toml.
• Fixed docs for aco & pso modules.
• Added CI for new example crate.

[co012]

👍