Fetcher refactor

[williamluer]

• Add unit tests to Fetcher
• Refactors Fetcher
• Splits Fetcher up into multiple files

TODO:

• Fix environment with jest
• Refactor to run correct tests with environment
• Move code to voyager
• Figure out why tests dont run
• Fix jsdom tests
• Add fetchImpl e2e tests
• Add FormDataWrapper tests

Current Issues:

• --env=node works but --env=jsdom fails due to an issue with Response
• Need to refactor tests to remove setNode and setBrowser and use RUNTIME created from the jest environment

There are still more things I would like to test:

• end to end fetchImpl tests. There are 6 return options but only 1 is tested.
• FormDataWrapper tests

Notes:

• Run tests with yarn workspace @fern-typescript/fetcher test
• Tests are currently failing to execute but I have not had time to investigate

Error: Qualified path resolution failed: we looked for the following paths, but none could be accessed.

Source path: /Users/williamluer/code/fern/fern/generators/typescript/babel.config.json
Not found: /Users/williamluer/code/fern/fern/generators/typescript/babel.config.json
Not found: /Users/williamluer/code/fern/fern/generators/typescript/babel.config.json.js
Not found: /Users/williamluer/code/fern/fern/generators/typescript/babel.config.json.json
Not found: /Users/williamluer/code/fern/fern/generators/typescript/babel.config.json.node
Not found: /Users/williamluer/code/fern/fern/generators/typescript/babel.config.json.ts
Not found: /Users/williamluer/code/fern/fern/generators/typescript/babel.config.json.tsx
Not found: /Users/williamluer/code/fern/fern/generators/typescript/babel.config.json.cjs
Not found: /Users/williamluer/code/fern/fern/generators/typescript/babel.config.json.jsx