fix: tabs not directly managing content

[danice]

Proposed changes

For tabs component: minor changes to maintain option to use only the tabs part, without managing the content associated to each tab.
This was working in previous version just not defining the href for each tab anchor element.

Types of changes

Just adding missing null / empty checks for href element.
In existing version there was this null checks in many places (for example in _setupNormalTabs method), but it was missing in some other places.

• Bug fix (non-breaking change which fixes an issue).
• New feature (non-breaking change which adds functionality).
• Breaking change (fix or feature that would cause existing functionality to change).

Checklist:

• I have read the CONTRIBUTING document.
• My commit messages follows the conventional commit format
• My change requires a change to the documentation, and updated it accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

[wuda-io]

LGTM