`volta list` output is wrong for locally-installed tools

In a project with a given tool installed locally (in this case, ember-cli)—

• Expected:

  $ volta list
  
  ⚡️ Currently active tools:
  
      Node: v12.16.2 (current @ /Users/chris/dev/test/foo/package.json)
      Yarn: v1.22.4 (current @ /Users/chris/dev/test/foo/package.json)
      Tool binaries available:
          ember (current @ /Users/chris/dev/test/foo/package.json)
  

• Actual:

  $ volta list
  
  ⚡️ Currently active tools:
  
      Node: v12.16.2 (current @ /Users/chris/dev/test/foo/package.json)
      Yarn: v1.22.4 (current @ /Users/chris/dev/test/foo/package.json)
      Tool binaries available:
          ember (default)
  

Additionally, we currently report the wrong platform values for these. In the extended form (volta list all):

• Expected:

  ember-cli@3.17.0 (current @ /Users/chris/dev/test/foo/package.json)
      binary tools: ember
      platform:
          runtime: node@12.16.2 (current @ /Users/chris/dev/test/foo/package.json)
          package manager: yarn@1.22.4 (current @ /Users/chris/dev/test/foo/package.json)
  

• Actual:

  ember-cli@3.17.0 (default)
      binary tools: ember
      platform:
          runtime: node@12.16.2
          package manager: npm@built-in
  

This correctly reports the Node version (though without the current @ ... from the design), but not the correct package manager version.

This affects both the --format=plain and the --format=human variants, which is expected: the underlying logic for both is identical.