feat: add conversion from different interval types

BREAKING CHANGES:
 - curying is left to the user
 - only accept array of interval instead of handling both case
 - only accept type that extends { start: number; end: number }

Author: Draeken

src/data.structures.ts

@@ -1,6 +1,4 @@
-export type interval = IntervalSE | IntervalFT | IntervalAR;
 export type roat<T> = ReadonlyArray<T>;
-export type roai = ReadonlyArray<interval>;
 
 export interface IntervalSE {
   start: number;