This patch opts into the `__screnshots__` folder snapshot management
for docker.
With this patch, docker-originating snapshots will be stored in the
following folder:
```
{testDir}/__screenshots__/{projectName}/{testFilePath}/{snapshotName}
```
Where `{testFilePath}` is a test file path relative to `testDir`
Drive-by: introduce and document the `PLAYWRIGHT_DOCKER` environment
variable that enables docker integration.
This patch introduces the following commands:
- `npx playwright docker build` that builds a VRT docker image
locally that is based off the `mcr.microsoft.com/playwright:jammy`
- `npx playwright docker start` that launches a docker container with
browsers.
- `npx playwright docker stop` that stops given docker container.
- `npx playwright docker test` that runs all the tests inside a
launched docker container.
