Add simultaneous update capability

[joselopeqti]

This PR addresses #1465.
It follows a similar pattern to the one used for simultaneous update #1411.

It adds the CL_COMMAND_BUFFER_CAPABILITY_SIMULTANEOUS_UPDATE_KHR capability, which allows developers to query if the implementation supports updating a command-buffer while an instance of the same is being ran.
If the capability is not supported, applications must wait for all previous submissions of the command-buffer to be finished before calling clUpdateMutableCommandsKHR.

It also fixes a wrong ifdef that was checking for cl_khr_command_buffer_multi_device instead of cl_khr_command_buffer_mutable_dispatch.

[EwanC]

Thanks for opening this, it's important to clarify to users if this is allowed, as it's an important use case to enable.

The current CTS test for non simultaneous-use workflow uses simultaneous-update behaviour by calling update without a blocking wait on the previous command-buffer enqueue. So all cl_khr_command_buffer_mutable_dispatch implementations that currently run and pass the mutable_dispatch_in_order/mutable_dispatch_out_of_order/mutable_dispatch_cross_queue tests should already support this behavior.

It would be interesting if that's been painful for any vendors and we should have this optional capability for simultaneous-update, or we can just make simultaneous-update required functionality for the extension and better specify that it is allowed.