* Enable Javascript bindings for photo module.

1. Enable the build flag in build_js.py.
2. Append js into WRAP list of photo’s CMakefiles.txt
3. Add photo module's API into JS API whitelist (embindgen.py)

Exposing the HDR imaging part of photo module.

[TODO]
Add tests
Fix opencv/doc/js_tutorials/

* [WIP] TODO: Add tests

* Remove TonemapDurand: algorithm patented in US, so moved to opencv_contrib

* Fix ningxin's comment: expose the base class.

* Add some more simple binding tests.

Also expose process function

* try to solve #13381

* Add note

* Added dependency verification mechanism for cmake

moved to CMakeFiles (no conflicts are expected)

* 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