test: Make E2E tests async & parallelizable

[mydea]

This PR makes the E2E test run async in child_process.spawn vs child_process.spawnSync), so we can parallelize them.

This required rather extensive refactoring of the E2E code, as making one piece of it async requires making everything async.

For now, we run 2 jobs in parallel on CI, 5 locally. We can adjust this later.

Some notes:

• We only log output of the child processes when a step fails, so we should have a cleaner log.
• We have to ensure to use a unique port for each job, as otherwise this fails when running in parallel. Keep this in mind when adding a new test app - it is passed process.env.PORT with a (hopefully) unique port.
• We consider a job to be parallelized a test-app, so if a test app has multiple jobs, they will still run in sequence.
• We copy each app into a temporary tmp dir now before we build it, as otherwise it cannot work when multiple versions are specified. This should be cleaned up after the test run.

Closes #7439

[github-actions]

size-limit report 📦

Path	Size
@sentry/browser - ES5 CDN Bundle (gzipped + minified)	20.62 KB (0%)
@sentry/browser - ES5 CDN Bundle (minified)	64.4 KB (0%)
@sentry/browser - ES6 CDN Bundle (gzipped + minified)	19.16 KB (+0.02% 🔺)
@sentry/browser - ES6 CDN Bundle (minified)	56.78 KB (0%)
@sentry/browser - Webpack (gzipped + minified)	21.53 KB (0%)
@sentry/browser - Webpack (minified)	72 KB (0%)
@sentry/react - Webpack (gzipped + minified)	21.55 KB (0%)
@sentry/nextjs Client - Webpack (gzipped + minified)	52.05 KB (0%)
@sentry/browser + @sentry/tracing - ES5 CDN Bundle (gzipped + minified)	28.21 KB (+0.01% 🔺)
@sentry/browser + @sentry/tracing - ES6 CDN Bundle (gzipped + minified)	26.41 KB (+0.01% 🔺)
@sentry/replay ES6 CDN Bundle (gzipped + minified)	44.74 KB (+0.01% 🔺)
@sentry/replay - Webpack (gzipped + minified)	38.86 KB (0%)
@sentry/browser + @sentry/tracing + @sentry/replay - ES6 CDN Bundle (gzipped + minified)	63.45 KB (+0.01% 🔺)
@sentry/browser + @sentry/replay - ES6 CDN Bundle (gzipped + minified)	56.49 KB (0%)

[mydea]

No idea why this is failing on CI at build of the E2E apps with e.g.:

Build failed for test application "nextjs-13-app-dir"
  [BUILD OUTPUT] [1/4] Resolving packages...
  [BUILD OUTPUT] [2/4] Fetching packages...
  [BUILD OUTPUT] info Visit https://yarnpkg.com/en/docs/cli/install for documentation about this command.
  [BUILD OUTPUT] 
  [BUILD OUTPUT] error http://localhost:4873/@sentry/utils/-/utils-7.43.0.tgz: Extracting tar content of undefined failed, the file appears to be corrupt: "ENOENT: no such file or directory, chmod '/home/runner/.cache/yarn/v6/npm-@sentry-utils-7.43.0-f2a49a3de5234bbbf2effef262d4e0f6d188be0b-integrity/node_modules/@sentry/utils/types/dsn.d.ts'"

if anybody has an idea, happy for pointers 😬