Compilation errors when using create-react-app and Babel macros

[csboling]

From the discussion in #317 I gather that the Babel macro setup ought to work out of the box with create-react-app, but I am unable to produce a working project. Here is my example repository showing an attempt.

To summarize:

• the default settings don't work because create-react-app forbids any imports outside of the src/ directory, so it refuses to import ../node_modules/.cache/src/... files.
• changing the cacheDir to src/.cache/ in an attempt to circumvent this restriction reports that the file .cache/src/ExchangeRates-GetRates.tsx is not found, although the file exists on disk. This is the same whether load or gql approaches from graphql-let/macro are used.