ESAP fit-&-finish issues for MS31 demo

In support of the summer 2021 demo, we'd like to address as many of these (ASTRON-internal) tickets as possible:

• SDC-235 - stay logged in when refreshing page
• SDC-244 - user friendly presentation of shopping basket items
• Add an “expert users” label to the API button (or remove it altogether if we don't need it).
• SDC-243 - enable un/re-selecting of shopping basket items before saving