LightGBM

Add capability to get possible max and min values for a model (#2737)

* Add capability to get possible max and min values for a model

* Change implementation to have return value in tree.cpp, change naming to upper and lower bound, move implementation to gdbt.cpp

* Update include/LightGBM/c_api.h

Co-Authored-By: Nikita Titov <nekit94-08@mail.ru>

* Change iteration to avoid potential overflow, add bindings to R and Python and a basic test

* Adjust test values

* Consider const correctness and multithreading protection

* Update test values

* Update test values

* Add test to check that model is exactly the same in all platforms

* Try to parse the model to get the expected values

* Try to parse the model to get the expected values

* Fix implementation, num_leaves can be lower than the leaf_value_ size

* Do not check for num_leaves to be smaller than actual size and get back to test with hardcoded value

* Change test order

* Add gpu_use_dp option in test

* Remove helper test method

* Update src/c_api.cpp

Co-Authored-By: Nikita Titov <nekit94-08@mail.ru>

* Update src/io/tree.cpp

Co-Authored-By: Nikita Titov <nekit94-08@mail.ru>

* Update src/io/tree.cpp

Co-Authored-By: Nikita Titov <nekit94-08@mail.ru>

* Update tests/python_package_test/test_basic.py

Co-Authored-By: Nikita Titov <nekit94-08@mail.ru>

* Remoove imports

Co-authored-by: Nikita Titov <nekit94-08@mail.ru>