Add ambient-display CCT LUT to Display White Balance

DisplayWhiteBalanceController currently maps display color temperature
to ambient color temperature exactly. This change introduces a lookup
table to allow mapping of display to ambient color temperature in user
configurable ways. Intermediate entries in the LUT are interpolated
linearly.

Bug 123966838
Test: manual.
      1. Ensure LUT logic does not initialize if it is configured in
      invalid ways: differing index and value lengths, less than 2
      indices or values, missing index or value series, missing both
      series.
      2. Test indexing into a correctly initialized LUT: below min,
      above max, LUT entries, and intermediate entries.
      Automation is tracked by bug 123866085.

Change-Id: Ie8651dc4e0005abf62100ff3a23e9acb4db1958d