Array lookups - JS side

[mitschabaude]

Create a TS API for the array lookup features exposed by @dannywillems with this task: https://github.com/MinaProtocol/mina/issues/13087

The API will likely consist of (at least) two constraint-creating methods:

• array_initialize(array: Field[]): void - fill an array with circuit variables
• array_get(array: Field[], index: Field): Field - look up a value in the array

The task for the SnarkyJS team is to package that as part of a nice API that makes array operations in a circuit easy. There's a lot of good prior work on this: #633

[stevenpack]

@garwalsh I moved this up the On Deck list for next sprint after ECDSA. Not a directive, but want to make sure it gets considered, as it looks like a smallish lift in o1js to unlock a significant capability.

[Trivo25]

see #90 #1062