[react] context generation for contract client instances

[pyramation]

We need some helpers to create contexts/providers for the client instances.

A good example of the client here:
https://github.com/EquilibriumEtf/frontend/blob/53e24aa7992bdaad85ec2a7c02a2e604a2d40897/client/core/index.ts#L27
https://gist.github.com/pyramation/05cebb95208accbcc76fbbe273211167

example of provider here:
https://github.com/EquilibriumEtf/frontend/blob/53e24aa7992bdaad85ec2a7c02a2e604a2d40897/client/react/client/EquilibriumProvider.tsx#L8
https://gist.github.com/pyramation/9db71d59e66694160d1194d291355c04

With a few changes:

• instead of all instances in one massive context, potentially have context for each client
• instead of wallet data, potentially just use address: string or whatever data is required