[Telemetry] Introduce getThermalInfo

This change adds a `os.telemetry.getThermalInfo` method to the
Telemetry Extension API.

This feature is currently behind a feature flag.

      2. browser_tests --gtest_filter="*TelemetryExtension*Display*"

Bug: b/299577174
Test: 1. unit_tests --gtest_filter="*TelemetryApi*Display*"
Change-Id: I97e21eb4dd9cb6e33ed19f9d3983714dc9ba69c1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5133321
Reviewed-by: Tim <tjudkins@chromium.org>
Code-Coverage: findit-for-me@appspot.gserviceaccount.com <findit-for-me@appspot.gserviceaccount.com>
Reviewed-by: Byron Lee <byronlee@chromium.org>
Reviewed-by: Kelvin Jiang <kelvinjiang@chromium.org>
Commit-Queue: Ethan Cheng <yycheng@google.com>
Cr-Commit-Position: refs/heads/main@{#1246323}