brightness: Add HasAmbientLightSensor to brightness delegate

Test: ash_unittests --gtest_filter=*BrightnessControllerChromeosTest*
Test: Tested downstream CL crrev.com/c/5422148 on my DUTs
Bug: b/328287584
Change-Id: I3e08a542ee0c5ca43c6a41c6e48372091b5a7631
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5420402


Reviewed-by: David Padlipsky <dpad@google.com>
Commit-Queue: Camden Bickel <cambickel@google.com>
Reviewed-by: Wenyu Zhang <zhangwenyu@google.com>
Cr-Commit-Position: refs/heads/main@{#1283379}