Bug 34557: (follow-up) Make link more like button in staff interface

Bug 34557: (follow-up) Make link more like button in staff interface

This patch adds Bootstrap button style to the link and changes the text
from "Load your checkouts" to "Show your checkouts."

The patch adds an anchor to the link so that the browser jumps down the
page a bit making the checkouts more visible.

The patch also corrects the includes for Font Awesome files. No icons
were loading because of incorrect asset links.

To test, follow the previous patch's test plan, checking that the button
looks correctly styled and that the page reloads with the checkout form
at the top.

Confirm that Font Awesome icons are loading throughout the page.

Signed-off-by: AndrewA <andrew.auld@ptfs-europe.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
(cherry picked from commit fbe06c7d9cb3f60d7b1553f462bbc9725d899fe9)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>