fix(hierarchy): bounds is a raw attribute, not a cross-platform key

Every native dump writes the rectangle out as a string under bounds, and
no DOM element carries an attribute of that name, so the key resolved
against the dump and matched nothing on web on every page there is. It
is accepted, so no unknown-key error said so, and no mapping can be
invented for it: there is no DOM fact to map it to.

Off the accepted list the web runtime raises the unknown-key error
instead of matching nothing in silence, and the key still resolves
wherever a producer writes it, through the escape hatch every other raw
attribute already uses: a key some element carries is a key that can
match, on both sides.

pkg/spec/test/fixtures/selector-keys.json

@@ -5,7 +5,6 @@
     "accessibilityText",
     "aria-label",
     "ariaLabel",
-    "bounds",
     "checked",
     "class",
     "className",
@@ -41,5 +40,5 @@
   "unknownKeyExample": [
     "descripton"
   ],
-  "unknownKeyMessage": "selector key \"descripton\" cannot match: no element carries that attribute, and it is not one of the accepted keys: accessibilityIdentifier, accessibilityLabel, accessibilityText, aria-label, ariaLabel, bounds, checked, class, className, clickable, content-desc, contentDescription, data-testid, desc, descPrefix, editable, elementType, enabled, focused, hintText, id, idPrefix, identifier, label, package, placeholder, placeholderValue, resource-id, scrollable, secure, selected, tag, testID, testTag, text, title, value"
+  "unknownKeyMessage": "selector key \"descripton\" cannot match: no element carries that attribute, and it is not one of the accepted keys: accessibilityIdentifier, accessibilityLabel, accessibilityText, aria-label, ariaLabel, checked, class, className, clickable, content-desc, contentDescription, data-testid, desc, descPrefix, editable, elementType, enabled, focused, hintText, id, idPrefix, identifier, label, package, placeholder, placeholderValue, resource-id, scrollable, secure, selected, tag, testID, testTag, text, title, value"
 }