Port `ignoreUnusedTypeExports` option of `no-unused-modules`

[silverwind]

I'm willing to port import-js/eslint-plugin-import#3011 into this module, it's a useful option to have.

[SukkaW]

@silverwind Sure! Please do. It is indeed a great option.

[silverwind]

Waiting a bit more for that PR to review/merge.

[SukkaW]

@silverwind You can backport here first since I can review PR quicker and more frequently. The test infra here is better as well.

[silverwind]

I have decided to disable no-unused-modules in my configs, so I'm sorry but I'm no longer interested in porting this option.

[silverwind]

Actually I gave it a second thought and would enable that rule again if ignoreUnusedTypeExports is supported, so here is the port: #116.