Save Noir ABI to disk

[joss-aztec]

Problem

It is not convenient to arrange the initial witness for a precompiled ACIR. At present, the Noir ABI is recompiled from source and held in memory for all nargo commands that require it.

Solution

Save the Noir ABI to disk when compiling from source, such that it can be used as a resource in a dApp. (Whether it is saved as a separate resource or incorporated into another is up for discussion.)

Alternatives considered

None, access to the Noir ABI is a must have for any sort of e2e system.

[TomAFrench]

Following discussion in slack, this will be bundled along with the acir.