* videoio(librealsense): fix pipeline start with config

fix to apply pipeline settings by passing config to start.

* videoio(librealsense): add support get props

add support get some props.

* Get/Set functions for BRISK parameters, issue #11527.

Allows setting threshold and octaves parameters after creating a brisk object. These parameters do not affect the initial pattern initialization and can be changed later without re-initialization.

* Fix doc parameter name.

* Brisk get/set functions tests. Check for correct value and make tests independent of default parameter values.

* Add dummy implementations for BRISK get/set functions not to break API in case someone has overloaded the Feature2d::BRISK interface. This makes BRISK different from the other detectors/descriptors on the other hand, where get/set functions are pure virtual in the interface.

DNN backends registry (#13332)

* Added dnn backends registry

* dnn: process DLIE/FPGA target

- use "random" area on input image
- avoid duplicate cases

* Added performance tests for hal::norm functions

* Added sum of absolute differences intrinsic

* norm implementation updated to use wide universal intrinsics

* improve and fix v_reduce_sad on VSX