Unify styling of FEM subject toolbar

[seanmiller26]

To coincide with the styling updates of the meta tools and video player toolbar, the subject toolbar is next in line to make FEM more consistent and address accessibility issues.

With all potential lab options added:

Main changes:
A non-responsive width of 45px, even at mobile.
Consistent button sizes of 40px.
Updated selected colors.
Field guide sizing, font and updated icon.

Challenge:
Show all marks, hide all marks, and show my marks is currently a dropdown. If we aim to put it in this toolbar, it may have to function by cycling through the 3 options. I do not have an icon for Show my marks at this time, and the one we currently use is not ideal. I am open to suggestions here, both on the functionality and any icons we can use.

Tooltips for marks:
When unselected: Hide all marks
When 'hide all' is selected: Hide my marks
When 'hide my marks' selected: Show all marks

Future considerations:
Rounded corners on the right.

Figma styling found here: https://www.figma.com/design/6rXVi6arrGTmoM08x9tpex/UI-Kit?node-id=387-1073&t=jylvf9bwvjFBi8JA-1