Cache file fetch/reads in memory in WASM prover

[nalinbhardwaj]

Since most webpages read these files for many steps, there's probably some mileage we can get on performance by caching these (or the internal/derived Rust structures) well. Not sure if the tradeoff will always make sense but probably worth investigating.

Nova-Scotia/src/circom/wasm_deps/generate_witness_browser.js

Lines 1 to 7 in 1bc7e39

	// TODO: can these reads be cached?
	export async function read_file_async(path) {
	const response = await fetch(path);
	const bytes = await response.arrayBuffer();
	const res = new Uint8Array(bytes);
	return res;
	}