refactor!: remove pnpDataPath

[paul-soporan]

What's the problem this PR addresses?

pnpDataPath is the only PnP file whose location can be customized, which means that:

• it's tied to the Yarn configuration
• it doesn't adhere to our new specification
• it makes it impossible for third-party tools implementing the PnP specification to use it without reading the Yarn configuration which doesn't make sense

How did you fix it?

Removed it.

Checklist

• I have read the Contributing Guide.

• I have set the packages that need to be released for my changes to be effective.

• I will check that all automated PR checks pass before the PR gets reviewed.