d2-common: Calendar: set event info text size in month view

As per https://github.com/aokpx-private/platform_packages_apps_Calendar/commit/dea658a69709404c3aad0d2bb82f203d7c4c2760 ...
Custom text sizes for event info in month view are now supported. The method
of implementation allows for text sizes to be set via overlay so they may
be adjusted by the device maintainer to suit their device's screen.

Change-Id: I91794461bdfc19387e395633209fc5713cc2ba74
Signed-off-by: Luis Cruz <ljc2491@gmail.com>