add a 'chronikNetworkProvider'

[mr-zwets]

We've just published BCHC v2 (based on BCHN) which can be run in place of an existing node, offering the same features as BCHN 28.0.0 but with the addition of the built in high performance Chronik indexer.

We have our public node running on https://bch.paybutton.org for those who want to try it out.

Documentation can be found here: https://docs.chronik.xyz/docs/chronik-js/connect

I think to use it with CashTokens there's still the need to use a special/experimental library

https://www.npmjs.com/package/chronik-client-cashtokens

[mr-zwets]

I started some initial experimentation in my own repo to implement a chronikNetworkProvider class

https://github.com/mr-zwets/chronik-test/blob/main/networkProvider.ts