Build swift-testing as part of the compat-suite toolchain

Various projects (vapor in particular) now depend on swift-testing. The
current Xcode installation doesn't contain it and we're not building it,
so they're failing. Update the base compat suite preset to also build
swift-testing (and its macros).

(cherry picked from commit 57331b2)

Author: bnbarham

utils/build-presets.ini

@@ -2944,13 +2944,17 @@ build-ninja
 llbuild
 swiftpm
 swift-driver
+swift-testing
+swift-testing-macros
 install-llbuild
 install-llvm
 install-static-linux-config
 install-swift
 install-swiftpm
 install-swift-driver
 install-swiftsyntax
+install-swift-testing
+install-swift-testing-macros
 reconfigure
 verbose-build
 skip-build-benchmarks