Update links to Halstack Provider in the Themes page

[GomezIvann]

Checklist

• Build process is done without errors and all tests pass in the /lib directory.
• Self-reviewed the code before submitting.
• Meets accessibility standards.
• Added/updated documentation to /website as needed.
• Added/updated tests as needed.

Description
Summary of changes:

• Some links were not pointing to the Halstack Provider page and were leading to a 'Page Not Found' error. The other ones were just pointing to the wrong URL.
• Solved issue Quick nav relative links affect the selected option of the sidenav #1527. Know there's a matchPaths function which takes into account relative paths with the "#" symbol.
• Solved issue Nav Tabs styling bug #1517. Updated the colour of the divider to match the Nav Tabs divider colour.