Modify Provider architecture to split it into packages

[forgetso]

The Provider repo contains various components that should be re-usable by the frontend captcha implementation and the user portal. Currently, these components are not split into packages but this is required for them to be reused.

Tasks

• Separate tasks into smaller, better defined files
• Move contract interface into package called @prosopo/contract
• Keep rest of provider package called @prosopo/provider-core
• Separate workspace for @prosopo/procaptcha that uses `@prosopo/contract'
• Build UI components package in @prosopo/procaptcha-ui etc.

Use nested typescript workspaces as example of structure: https://github.com/forgetso/typescript-yarn-nested-workspaces

Later

Split provider into other packages

[forgetso]

Work being carried out in branches called workspaces