[R-package] automate release process for R

[jameslamb]

See #3071 (comment) for background. To close this issue, implement the solution in that comment or some other approach that allows for building a release of the R package without manually updating anything other than VERSION.txt

[jameslamb]

this should also include automating the creation of binaries: #3188 (comment)

UPD: We decided to not release binaries:

I know #3283 mentioned creating binaries but I don't think LightGBM should do that, now that the R package is on CRAN and CRAN prepares binaries automatically.
#4117 (review)

[jameslamb]

this should also include creating an artifact with the source distribution we'd upload to CRAN: #3285 (comment)

[jameslamb]

When I pick this up, I want to be sure to include in the release notes a shout-out to the maintainers of curso-r/rightgbm#2 who have already done good work figuring out a process for some of this.

[github-actions]

This issue has been automatically locked since there has not been any recent activity since it was closed. To start a new related discussion, open a new issue at https://github.com/microsoft/LightGBM/issues including a reference to this.