Support custom score API URL for testing

[mktcode]

Analogous to: snapshot-labs/snapshot-v1#918
We could replace:

snapshot.js/src/utils.ts

Line 22 in 81f100e

export const SNAPSHOT_SCORE_API = 'https://score.snapshot.org/api/scores';

...with an optional last parameter here:

snapshot.js/src/utils.ts

Lines 115 to 122 in 81f100e

	export async function getScores(
	space: string,
	strategies: any[],
	network: string,
	provider: StaticJsonRpcProvider | string,
	addresses: string[],
	snapshot: number | string = 'latest'
	) {

...defaulting to https://score.snapshot.org if not set of course.

[bonustrack]

Also the "provider" param is not necessary anymore, we can remove it and add the score api url as last param

[mktcode]

I'll do that quickly...