vulkan: advertise VK_EXT_debug_report

We use VK_EXT_debug_report to report most messages and we should always
advertise the extension.  This is complicated however because the HAL may
also advertise the extension.

Do the minimal and cache whether the HAL supports VK_EXT_debug_report in
class Hal.  More refactorings will be required if we want to be more
flexible.

Bug: 28753291
Change-Id: I0298b2c3024e2ed059411128dbbe264c0b289a4b