Planner tests: memo

[grod220]

Test various cases for memo handling:

web/packages/wasm/crate/src/planner.rs

Lines 709 to 719 in 8bf66ea

	// Add memo to the transaction plan.
	let memo = if let Some(pb_memo_plaintext) = request.memo {
	Some(MemoPlan::new(&mut OsRng, pb_memo_plaintext.try_into()?))
	} else if actions_list.requires_memo() {
	// If a memo was not provided, but is required (because we have outputs),
	// auto-create one with the change address.
	let plaintext = MemoPlaintext::new(change_address, String::new())?;
	Some(MemoPlan::new(&mut OsRng, plaintext))
	} else {
	None
	};