Static Constructors (Tree-Shaking)

[ScottyPoi]

All static constructors in EthereumJS packages were removed as part of tree-shaking optimizations.

Ultralight's portalnetwork package contains several static constructors. PortalNetwork.create is a big one, but also uTP packet constructors Packet.from... and possibly more.

To follow the optimization pattern executed in the EthJS packages, we would replace these static constructors with an exported function. For example, in the PortalNetwork class, public static create = async (...) => {...} would be replaced with export async function createPortalNetwork(...) {...} with the same internal logic, and moved to a new file client/constructor.ts

[cjustinobi]

@ScottyPoi please check the PR
Will create a separate PR for the uTP etc.

[acolytec3]

Have merged #757 which partially completes this work. Thanks @cjustinobi!