LightGBM

[R-package][ci] Added more R linters (fixes #2477) (#2533)

* Added more linters on R code

* started working on implicit integers

* finished style changes to handle implicit integers

* regenned documentation and added concatenation linter

* changed channel for r-lintr

* try building stringi before lintr

* trying to get libicui18n

* trying another thing

* trying conda-forge again

* added re-install of stringi

* uncommented other stages

* Update .ci/test.sh

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

* removed apt update and changed lintr version floor

* get lintr from CRAN

* R needs to come before C++ linting

* testing lintr install from CRAN

* trying one more thing

* more verbose

* order might matter

* removed commented code

* cleaned up linting block in test.sh

* grouped conda install calls and fixed a few integer array things