feat(hierarchy): an element reports whether it masks what is typed into it

ios reads it off SecureTextField, which the companion already sent and
nothing read; web reads input[type=password]. Android cannot: the native
tree mapper drops the password attribute before the sidecar sees it, so
the fact is three-valued and null there rather than a false that would
read as "not secure".

internal/driver/chrome/testdata/element-state.html

@@ -11,6 +11,7 @@
     <input id="toggle-all" type="checkbox" />
     <input id="toggle-done" type="checkbox" checked />
     <input id="editing" type="text" value="buy milk" />
+    <input id="secret" type="password" />
     <button id="save">save</button>
     <button id="cancel" disabled>cancel</button>
     <select id="filter">