feat(web,a11y): standardize the FullScreenModal UI (#8566)

* feat(web,a11y): standardize the FullScreenModal look

* consistent header, padding, close button, and radius as BaseModal
* vertically stacking ConfirmDialogue CTA buttons in narrow screens
* adding aria-modal tags for screen reader
* add viewport-specific height limits on modals, to enable scrolling
* prevent focus from being hidden under sticky content in modals
* standardize FullScreenModal widths using a Prop

* wip: consistent padding with header

* fix: alignment on "create user" and "edit user" modals

* fix: horizontal modal content alignment

* fix: create user CTA buttons

* chore: remove unnecessary warning

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Co-authored-by: Jason Rasmussen <jrasm91@gmail.com>

web/src/lib/components/user-settings-page/partner-settings.svelte

@@ -189,6 +189,7 @@
 
 {#if removePartnerDto}
   <ConfirmDialogue
+    id="stop-sharing-photos-modal"
     title="Stop sharing your photos?"
     prompt="{removePartnerDto.name} will no longer be able to access your photos."
     onClose={() => (removePartnerDto = null)}