feat: multiple resolve targets when parsing manifest

[brpowell]

What does this PR do?

Allows specifying multiple targets to resolve source components from a manifest against. This covers the use case of resolving source components for multiple package directories.

const ws = await WorkingSet.fromManifestFile('package.xml', {
  resolve: ['/path/to/force-app', '/path/to/test-app', '/path/to/another-one']
});

// or

const ws = await WorkingSet.fromManifestFile('package.xml', {
  resolve: '/path/to/force-app'
});

What issues does this PR fix or reference?

@W-8507891@