layers:Delay barrier validation for secondary CB

layers:Delay barrier validation for secondary CB

When a secondary command buffer doesn't have a framebuffer, queue up
any renderPass barrier validation until submit time when we know we'll
have a framebuffer bound.

Added a separate vector of validation functions that are added to
secondary command buffer for this case and then executed at
CmdExecuteCommands() time.

Migrated the image validation that needs to be delayed to its own
function. This makes it easy to add to the delayed function array and
capture a copy of the image barrier that needs to be validated.
In CmdExecuteCommands() when validation runs inherit the activeFB
from the primaryCB into the secondary CB.