Make NodeResolver check realpath before resolving with source entry

[g6123]

↪️ Pull Request

• Some modern package managers (pnpm and Yarn berry with nodeLinker: pnpm) save dependencies in their internal storage, and make symlinks to them in node_modules directory.
• This comes problematic when Parcel is resolving source entry, because NodeResolver thinks dependencies behind symlinks are actually links to workspaces in the same monorepo, which is a false assumption in this case.
• This PR tries to handle this problem by checking if the realpath to the dependency includes node_modules, and if it does, ignoring source entry.
• Fixes Parcel tries to import source of dependency instead of main or module even if it does not exist #7610
• Fixes package.json#source field is used for npm packages with pnpm #5784

💻 Examples

For example, in the case of pnpm with default settings:

workspace/
  node_modules/
    .pnpm/[email protected]/node_modules/compute-scroll-into-view/
      package.json
    compute-scroll-into-view/ -> symlink to .pnpm/[email protected]/node_modules/compute-scroll-into-view
package.json

When trying to import compute-scroll-into-view from workspace, node_modules/compute-scroll-into-view/ is a symbolic link. So Parcel tries to read source field of compute-scroll-into-view, which points to an non-existing file.

🚨 Test instructions

I think the included test covers sufficient cases 🤔

✔️ PR Todo

• Added/updated unit tests for this change
• Filled out test instructions (In case there aren't any unit tests)
• Included links to related issues/PRs