fix: node 18 native fetch support

[moltar]

This is just a quick POC, not an actual final implementation.

Looks like there is an issue on the Polly side:

Tests throw with:

    TypeError: Cannot assign to read only property 'Request' of object '[object global]'

      32 | // eslint-disable-next-line jest/require-top-level-describe
      33 | beforeEach(() => {
    > 34 |   jestPollyContext.polly.configure(jestPollyConfigService.config)
         |                          ^
      35 |   jestPollyContext.polly.server
      36 |     .any()
      37 |     .on('beforePersist', (request, recording: PollyRecording) => {

      at FetchAdapter.onConnect (node_modules/@pollyjs/adapter-fetch/src/index.js:53:5)
          at Array.forEach (<anonymous>)
      at Object.<anonymous> (src/jest-polly.ts:34:26)

Which seems to be coming from here:

https://github.com/Netflix/pollyjs/blob/2d7f0f33d9f552e78f0dfe81179751b4692357be/packages/%40pollyjs/adapter-fetch/src/index.js#L53

Closes #342

[moltar]

Looks like Polly node adapter is using nock, which does not yet have support for Node 18.

See this issue, which links to two other issues: nock/nock#2397

[moltar]

Might be part-solved by #388