Documentation generation refactoring (#10621)
* Documentation build updates:
- disable documentation by default, do not add to ALL target
- combine Doxygen and Javadoc
- optimize Doxygen html
* javadoc: fix path in build directory
* cmake: fix "Documentation" status line
[~] Automatically tracked dependencies between modules
[+] Support for optional module dependencies
[+] Options to choose modules to build
[~] Removed hardcoded modules lists from OpenCVConfig.cmake, opencv.pc and OpenCV.mk
[+] Added COMPONENTS support for FIND_PACKAGE(OpenCV)
[~] haartraining and traincascade are moved outside of modules folder since they aren't the modules