feat(web,a11y): consolidate BaseModal into FullScreenModal (#8787)

* feat(web,a11y): FullScreenModal sticky buttons

* chore(web): combine BaseModal into FullScreenModal

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Co-authored-by: Alex <alex.tran1502@gmail.com>

web/src/lib/components/shared-components/change-date.svelte

@@ -65,7 +65,6 @@
   <ConfirmDialogue
     id="edit-date-time-modal"
     confirmColor="primary"
-    cancelColor="secondary"
     title="Edit date and time"
     prompt="Please select a new date:"
     disabled={!date.isValid}