Update where responsive grid cell icon size is defined

This CL changes where the cell icon size, text size and drawable padding is defined to prevent an issue with taskbar.
The transient taskbar updates the DeviceProfile icon size with a different value than used for responsive grids, and this update wasn't working anymore because responsive grid implementation wasn't reading the value from iconSize inside the updateIconSize function, but from the responsive grid spec.

Bug: 313463280
Flag: ACONFIG com.android.launcher3.enable_responsive_workspace TEAMFOOD
Test: manual
Test: NexusLauncherImageTests
Change-Id: I835a90d724c2d1b2d32f483b758b789be7cbdcfe