Use Map for runtime Device/Group lookups.

[Nerivec]

Improved test to cover all cases where lookups should be synced.
Fixed group getter return type.

Also marked functions changed for iterator versions in previous PR as deprecated. Pretty sure they can just be removed, but need to double-check and update tests (used in expect in a few places). Also might want to instead rename xyzIterator to xyz for cleaner names. Can be dealt with in another PR.

[Nerivec]

We could also optimize Device lookup by nwk addr with a Map<number, string>:

    public static byNetworkAddress(networkAddress: number, includeDeleted: boolean = false): Device | undefined {
        Device.loadFromDatabaseIfNecessary();

        const ieeeAddr = Device.nwkToIeeeCache.get(networkAddress);

        return ieeeAddr ? Device.byIeeeAddr(ieeeAddr, includeDeleted) : undefined;
    }

With cache updated in create, loadFromDatabaseIfNecessary and changeIeeeAddress functions.

[Koenkk]

We could also optimize Device lookup by nwk addr with a Map<number, string>:

Sounds good!

[Koenkk]

Thanks!