[tint][utils] Add light theme, detect dark / light

Add a new tint `--color` command line flag to explicitly control color
output and theme.

Change-Id: I54bbdf8ecb86dfdd0c74e020b2858a81850a6102
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/176120
Reviewed-by: dan sinclair <dsinclair@chromium.org>
Commit-Queue: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
diff --git a/src/tint/utils/BUILD.cmake b/src/tint/utils/BUILD.cmake
index badeb73..1771b07 100644
--- a/src/tint/utils/BUILD.cmake
+++ b/src/tint/utils/BUILD.cmake
@@ -53,5 +53,6 @@
 include(utils/socket/BUILD.cmake)
 include(utils/strconv/BUILD.cmake)
 include(utils/symbol/BUILD.cmake)
+include(utils/system/BUILD.cmake)
 include(utils/text/BUILD.cmake)
 include(utils/traits/BUILD.cmake)