Group @testable imports at the bottom, per public/rules-swift's swiftformat. A
behavior-preserving import-ordering reformat across 252 files (mostly tests).
--trailingclosures was deliberately not adopted (cosmetic, and swiftformat flags
it as caution-worthy).
XSD 1.0 §3.4.6 (cvc-complex-type) allows an element at most one attribute whose
type is xs:ID. A complex type that DECLARES two ID-typed attribute uses is already
a compile-time schema error, but two ID-typed attributes can also reach an element
through an xs:anyAttribute wildcard that admits two ID-typed global attributes
(attZ014), which was accepted.
validateAttributes now counts the present attributes whose effective type is
xs:ID, taking the type from the declared use an attribute matches or the global
declaration a matching wildcard admits (so a restriction of xs:ID counts), and
reports an error when more than one is present. xs:IDREF/xs:ENTITY and a single
ID attribute are unaffected, and a valid instance never carries two, so the check
cannot over-reject.
invalid-instances-accepted 45 to 43, no false positive (valid-instances-rejected
and valid-schemas-rejected held at 0), no other bucket moved.
