remove safari special-casing for paste (#1470)

Previously, we had a bunch of special-casing around paste to support
safari quirks on desktop and ios.

Since upgrading radix-ui and useGesture, these are no longer needed and
were actually causing issues. This diff removes the special casing for
paste and makes it a normal action that get triggered the same way as
any other.

### Change Type
- [x] `patch` — Bug Fix

### Test Plan

1. Copy text outside of tldraw, paste in tldraw with the context menu,
edit menu, and keyboard shortcut
2. Repeat for images outside of tldraw
3. Repeat for shapes inside of tldraw

### Release Notes

[fixes a regression introduced during this release]

packages/ui/src/lib/hooks/useMenuSchema.tsx

@@ -97,12 +97,7 @@ export function MenuSchemaProvider({ overrides, children }: MenuSchemaProviderPr
 						'clipboard-actions',
 						menuItem(actions['cut'], { disabled: noneSelected }),
 						menuItem(actions['copy'], { disabled: noneSelected }),
-						{
-							id: 'MENU_PASTE',
-							type: 'custom',
-							disabled: !showMenuPaste,
-							readonlyOk: false,
-						}
+						menuItem(actions['paste'], { disabled: !showMenuPaste })
 					),
 					menuGroup(
 						'conversions',