Millisecond Duration & Expiration Separation

[crnbarr93]

Description

The current implementation of `MillisecondsDuration/MillisecondsExpiration` does not generate a different type in our schemas. The intent was to improve UX generated by our schemas but this implementation failed to do so.

We should completely separate these types as two indepdendent structs and change Milliseconds to be a trait that these two types implement.

Implementation

Instead of using aliases use structs:

pub struct MillisecondsDuration(u64);
pub struct MillisecondsExpiration(u64);

Alter Milliseconds to be a trait:

pub trait Milliseconds {
    fn is_expired(&self, block: &BlockInfo) -> Milliseconds;
    //...
}

Implement the new Milliseconds trait for MillisecondsDuration and MillisecondsExpiration.

Acceptance Criteria

• MillisecondsDuration struct
• MillisecondsExpiration struct
• Milliseconds trait
• Updated unit-testing where appropriate