This defines the kcmdline_prop context for properties controlled by
kcmdlinectrl, and defines a property called kcmdline.binder for
switching between the Rust and C implementations of the Binder driver.
It is intended that additional kcmdline properties introduced in the
future would share the same kcmdline_prop context.
Test: Verified that setprop/getprop work and that the value is loaded properly at boot
Bug: 326222756
Change-Id: Iea362df98d729ee110b6058c6e5fa6b6ace03d8e
