G-API-NG/Streaming: don't require explicit metadata in compileStreaming()

* First probably working version
Hardcode gose to setSource() :)

* Pre final version of move metadata declaration from compileStreaming() to setSource().

* G-API-NG/Streaming: recovered the existing Streaming functionality

- The auto-meta test is disabling since it crashes.
- Restored .gitignore

* G-API-NG/Streaming: Made the meta-less compileStreaming() work

- Works fine even with OpenCV backend;
- Fluid doesn't support such kind of compilation so far - to be fixed

* G-API-NG/Streaming: Fix Fluid to support meta-less compilation

- Introduced a notion of metadata-sensitive passes and slightly
  refactored GCompiler and GFluidBackend to support that
- Fixed a TwoVideoSourcesFail test on streaming

* Add three smoke streaming tests to gapi_streaming_tests.
All three teste run pipeline with two different input sets
1) SmokeTest_Two_Const_Mats test run pipeline with two const Mats
2) SmokeTest_One_Video_One_Const_Scalar test run pipleline with Mat(video source) and const Scalar
3) SmokeTest_One_Video_One_Const_Vector test run pipeline with Mat(video source) and const Vector
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* style fix

* Some review stuff

* Some review stuff

* Support nGraph

* Fix resize

* Added Swish and Mish activations

* Fixed whitespace errors

* Kernel implementation done

* Added function for launching kernel

* Changed type of 1.0

* Attempt to add test for Swish and Mish

* Resolving type mismatch for log

* exp from device

* Use log1pexp instead of adding 1

* Added openCL kernels

Tests for argument conversion of Python bindings generator

* Tests for parsing elemental types from Python bindings

  - Add positive and negative tests for int, float, double, size_t,
    const char*, bool.
  - Tests with wrong conversion behavior are skipped.

* Move implicit conversion of bool to integer/floating types to wrong
conversion behavior.

Fix incorrect use of std::move() in g-api perf tests

* First version

* Fix perfomace tests

Replace

    c.apply(...);

with

    cc = c.compile(...);
    cc(...);

* Remove output meta arguments from .compile()

* Style fix

* Remove useless commented string

* Stick to common pattern : i.e. use gin() and gout() explicitly.

* Use cc(gin(...), gout(...)) in all cases.

G-API: Implement PlaidML2 backend

* PlaidML backend init version

* Add test

* Support multiply inputs/outputs in PlaidML2 backend

* Fix comment to review

* Add HAVE_PLAIDML macros

* Move plaidml tests to separate file

* Fix comment to review

* Fix cmake warning

* Fix comments to review

* Fix typos

overload -> overflow

* Fix comments to review

* Clean up

* Remove spaces from cmake scripts
* Disable tests with bitwise operations

* Use plaidml::exec::Binder

G-API: Introduced Security Barrier & Interactive Face Detection samples

* G-API-NG/Samples: Added samples & relevant changes

- Security barrier camera sample
- Age/Gender/Emotions recognition sample
- GIEBackend now loads CPU extension libraries
- A couple of API-level workarounds added to deal with cv::Mat/Blob conversions

* G-API-NG/Samples: removed HAVE_INF_ENGINE remnants

- apply tag 'skip_other'

ml: refactored tests

* use parametrized tests where appropriate
* use stable theRNG in most tests
* use modern style with EXPECT_/ASSERT_ checks