Add volume control to bottom panel

Changes:
- Import a reworked version of the KUKSA.val client code from the
  Flutter dashboard app, with the aggregated signal Riverpod provider
  replaced with per-signal providers for the signal the homescreen
  needs and a couple of temperature ones it might use.  Using separate
  providers is more in-line with recommended Riverpod best practices.
- Various tweaks to enable using Riverpod.
- Split the bottom panel out into its own widget, and add a stack in
  it to layer the default logo panel with the volume control slider,
  which has been added as a new widget definition to provide the hook
  to drive timer based lowering behavior like the Qt homescreen does.
- The KUKSA.val connection widget has been added to the bottom panel
  rather than overriding the top-level widget as in the dashboard and
  HVAC apps.  This seems preferable with respect to still providing
  some functionality in the event KUKSA.val is unavailable.
- Remove the old demo dashboard and HVAC pages that are now unused,
  along with the image assets they needed, to allow cleaning up
  pubspec.yaml and ease maintenance.

Bug-AGL: SPEC-4659

Signed-off-by: Scott Murray <scott.murray@konsulko.com>
Change-Id: I5d9180a3461948a58321564e71134c4961ce0ef7

1 files changed, 0 insertions, 0 deletions

diff --git a/images/HMI_HVAC_ChairIndicator_OFF.png b/images/HMI_HVAC_ChairIndicator_OFF.png
deleted file mode 100644
index 510930f..0000000
--- a/images/HMI_HVAC_ChairIndicator_OFF.png
+++ /dev/null