Investigate if we can support null as snapshot on EVM networks

[Sekhmet]

Currently we enforce snapshot block to not be null on EVM:

sx-monorepo/apps/ui/src/networks/evm/actions.ts

Lines 717 to 718 in 4627095

	if (snapshotInfo.at === null)
	throw new Error('EVM requires block number to be defined');

I'm not longer sure why that's the case, quick look at EVM strategies suggests that it might actually work, just using blockTag: "latest" if block is null.

We should verify if that's possible and implement it so we don't have this extra logic inside.