Add pagination component

[broccolini]

To be moved from github/github to Primer.
Docs: https://styleguide.github.com/primer/components/pagination/

• Update styleguide to not include manually added pagination component

[broccolini]

Heads up, this issue can only done by GitHub staff.

[whytrall]

Is pagination component something like this?

If yes, the same thing can be done using BtnGroup: