chore: clean up a bunch of legacy styles (#5973)

* remove unused experimental-styles-within

* remove unused styles

* more cleanup + prepr

* Refactor nearly all legacy buttons to use ButtonStyled

* prepr

* Update MC account selector to modern version

* prepr

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Co-authored-by: Calum H. <calum@modrinth.com>

apps/app-frontend/src/components/ui/modal/ModpackAlreadyInstalledModal.vue

@@ -11,7 +11,7 @@
 		<template #actions>
 			<div class="flex gap-2 justify-end">
 				<ButtonStyled type="outlined">
-					<button class="!border !border-surface-4" @click="handleCancel">
+					<button @click="handleCancel">
 						<XIcon />
 						{{ formatMessage(commonMessages.cancelButton) }}
 					</button>