G-API: Introduce new `reshape()` API (#12990)

* Moved initFluidUnits, initLineConsumption, calcLatency, calcSkew to separate functions

* Added Fluid::View::allocate method (moved allocation logic from constructor)

* Changed util::zip to util::indexed, utilized collectInputMeta in GFluidExecutable constructor

* Added makeReshape method to FluidExecutable

* Removed m_outputRoi from GFluidExecutable

* Added reshape feature

* Added switch of resize mapper if agent ratio was changed

* Added more TODOs and renamed a function

* G-API reshape(): add missing `override` specifiers

Fix warnings on all platforms