GitLab

* [R-package] [docs] fix calculation of R test coverage (fixes #4919)

* use quotes

* use in_covr() instead of env variable

* Update R-package/README.md
Co-authored-by: Nikita Titov <nekit94-08@mail.ru>

* check that covr exists

* add covr to suggests

* use R_COVR environment variable

* Update R-package/tests/testthat/test_lgb.unloader.R
Co-authored-by: Nikita Titov <nekit94-08@mail.ru>
Co-authored-by: Nikita Titov <nekit94-08@mail.ru>

* [R-package] reduce verbosity in some unit tests

* simplify

* Update R-package/tests/testthat/test_lgb.plot.interpretation.R

* [R-package] remove support for '...' in lgb.train()

* Apply suggestions from code review
Co-authored-by: Nikita Titov <nekit94-08@mail.ru>
Co-authored-by: Nikita Titov <nekit94-08@mail.ru>

* [R-package] Add tests on lgb.check.eval, lgb.unloader, and lgb.encode.char

* remove accidental test file

* regenerated docs