bug: Push siloed nullifier to pendingNullifiers

[suyash67]

The pendingNullifiers is used to filter out notes that are already spent. But currently while filtering, we compare a siloed nullifier with an inner nullifier:

aztec-packages/yarn-project/acir-simulator/src/client/client_execution_context.ts

Lines 133 to 134 in 91bb1a9

	// Remove notes which were already nullified during this transaction.
	const dbNotesFiltered = dbNotes.filter(n => !this.pendingNullifiers.has(n.siloedNullifier as Fr));

This PR fixes it by adding a siloed nullifier to pendingNullifiers.

[dbanks12]

lgtm