https://plugins.jetbrains.com/plugin/17718-github-copilot/ve...
EDIT: Hmm, it installed but it refuses to run.
EDIT2: Looks like you can force the plugin to work by editing the plugin.xml contained in github-copilot-intellij-1.0.1.jar within the plugin archive. Just remove the line that includes Rider as incompatible. The same should work for CLion.