Enhance valid-track to check for clashing fields

[pmdartus]

The following code should fail the valid-track rule:

class Foo {
  @track openModal = false;
  
  openModal;
  // ^ Property clashing with existing tracked fields
 
  openModal() {}
  // ^ Method clashing with existing tracked fields
}

Notes:

• We need to validate that valid-api and valid-wire rules are also subject to this issue where a field is shadowed by another field or method with the same name.
• This check should be added behind a flag (prior art: feat: add rule for properties containing both underscores and uppercase charactacters #54) because those rules run whenever a component is published to the Salesforce platform. Without a flag might cause LWC components not being able to the re-published.

[git2gus]

This issue has been linked to a new work item: W-8651062

[pmdartus]

Thanks to @jodarove (#25 (comment)), there is actually no work needed here. The lwc/no-dupe-class-members already covers this case.