Accessibility: advanced search form

[qqmyers]

Overview of the Feature Request
The advanced search form shows tens of accessibility warnings in tools such as Deque's AXE. All of these appear to be from inputs not being associated with labels.

What kind of user is the feature intended for?
(Example users roles: API User, Curator, Depositor, Guest, Superuser, Sysadmin)

What inspired the request?
QDR is going through Dataverse to find/address accessibilities issues. Some of those appear to be straight forward while others may involve discussion. So this issue is one of many where I'll try to break out reasonable-sized (to me) issues where I can make PRs.

Any related open or closed issues to this feature request?
There are some accessibilities issues - not sure there's a specific one related to this.