Support Rider properly

[cja-github]

As per https://github.com/JetBrains/resharper-rider-samples/blob/master/.gitignore and https://rider-support.jetbrains.com/hc/en-us/articles/207097529

[scscgit]

Could we have this moved from Global to a root directory, just like VisualStudio.gitignore? For about a year there hasn't been any way to create a JetBrains-compatible project using https://github.com/new due to this removal of Rider compatibility: 96baa63

[scscgit]

• Also is there any plan to support Shared Run Configurations? In Rider it can be like .idea/.idea.NameOfTheProject/.idea/runConfigurations/ with a variable project name (created using "Store as a project file" in the right-top corner of Run Configurations window), while in IDEA it's like .idea/runConfigurations

EDIT: Actually I noticed this is supported implicitly by not being excluded, so I'll instead point out that files under .idea like .name, encodings.xml, indexLayout.xml, or vcs.xml are now being created by default even in a simplest project, even though files like .editorconfig are meant to handle encoding, and the other settings don't have an impact on users who use Visual Studio, while storing their defaults doesn't make any sense, so adding them is far from self-evident, and I would argue against adding them "by default" - they can always be uncommented when needed. Adding so much auto-generated boilerplate by default harms any Rider users for no reason when they join Visual Studio projects. Hopefully there's some compromise to be made, e.g. leaving this "official" way in Global directory, while making a generic VisualStudio or C# .gitignore that removes these files by default. In other words, I think this commit should be simply reverted: 96baa63