Improve accessibility of Pagination component

[helrond]

Is your feature request related to a problem? Please describe.

The accessibility of the Pagination component can be improved.

Describe the solution you'd like

• Remove tabindex values
• remove role="button" attributes
• Update the truncated pages button:
  • add the disabled class and aria-disabled=true to the link.
  • add an aria-label attribute that says "truncated pages"

Additional context

The pagination on Argo may be a good pattern to refer to, since that has received recent attention.