T: set toolchain by `WithRustup` project descriptor
T: set toolchain by `WithRustup` project descriptor

It should help to write light tests where toolchain is needed

intellij-rust/intellij-rust,Undin/intellij-rust,Undin/intellij-rust,Undin/intellij-rust,intellij-rust/intellij-rust,intellij-rust/intellij-rust,intellij-rust/intellij-rust,Undin/intellij-rust,intellij-rust/intellij-rust,Undin/intellij-rust,Undin/intellij-rust,intellij-rust/intellij-rust