[G-API]: Add Fluid bitwise operations implementation for (GMat, GScalar)
* Added Fluid `bitwise` with `Scalar` + acc.tests
- simple loop implementation for Fluid used (no `hal`);
- `Scalar` is casted to `int` in the beginning
- tests just modified to work with `Scalar`
- expected output in operators' tests fixed (operators can't change Mat's depth)
- `float` `Scalar` `RNG` added, `RNG` reworked (`time` is used now), initialization of test fixtures reworked
- if input or output is `float` Scalar is initialized by `float`
- some problems with Fluid/OCV floating-point comparison difference stashed by `AbsSimilarPoints()` usage, FIXME added
- divide-by-zero is now fixed differently and everywhere
* - Added perf_tests for bitwise_Scalar operations
- due to errors of Fluid floating-point comparison operations, added support of different validation in Cmp perf_tests; added FIXME
- reworked integral initialization of Scalar
* Addressing comments
- NULL -> nullptr
- Scalar convertion moved to the function
- avoid -> avoiding
* Addressing comments
* CV_assert -> GAPI_assert
* Addressed DM comments
- refactored convertScalarForBitwise()
- removed unnecessary braces for switch
* Changed the operators tests
- switch via `enum` implemented
- infrastructure for that refactored
[G-API]: Add four kernels to parse NN outputs & provide information in Streaming scenarios
* Kernels from GL "blue" branch, acc and perf tests
* Code cleanup
* Output fix
* Comment fix
* Added new file for parsers, stylistic corrections
* Added end line
* Namespace fix
* Code cleanup
* nnparsers.hpp moved to gapi/infer/, nnparsers -> parsers
* Removed cv:: from parsers.hpp
[G-API]: Add GArray initialization support
* Added GArray initialization (CONST_VALUE, GScalar analog) and test for this
* Whitespaces
* And one more space
* Trailing whitespace
* Test name changed. Build with magic commands.
* GArray works with rvalue initialization
* Code cleanup
* Ternary operator in the initialization list.
Fix KD Tree kNN Implementation
* Make KDTree mode in kNN functional
remove docs and revert change
Make KDTree mode in kNN functional
spacing
Make KDTree mode in kNN functional
fix window compilations warnings
Make KDTree mode in kNN functional
fix window compilations warnings
Make KDTree mode in kNN functional
casting
Make KDTree mode in kNN functional
formatting
Make KDTree mode in kNN functional
* test coding style
[G-API]: Relocation of operators' overloads
* Relocates overloaded operators for `cv::GMat` and `cv::GScalar` to `cv::` namespace
- adds test to check usage of operators compilation
* Add tests for all the operators
* Address comments
