Ensure all adapters are using newest patterns

[justinkaseman]

**There are adapters that exist in the mono-repo that may be missing some of the following:

• using the file structure shown in the example source adapter with /endpoints folder
• using endpointSelector patterns seen in adapter.ts
• using module exports
• exporting their package specific types

They should be migrated to the newer style (see example adapters)**
https://github.com/smartcontractkit/external-adapters-js/tree/develop/packages/examples/source

[austinborn]

Are there specific examples of lack of module exports, or missing package type exports? The first two are clear and generally-applicable, but I don't know what the requirements are for the last two.

[austinborn]

Progress for endpoints folder and endpointSelector pattern will be tracked here:
https://docs.google.com/spreadsheets/d/1JZMADFZxihNOVHmmfZDCHa8IzsjlGgt9yemEWfMsd7U/edit#gid=0

[austinborn]

@bogos @karen-stepanyan For now, only worry about the endpoints folder and endpointSelector pattern