Intellij-rust: Collapse use statements

[itmuckel]

Some of my rust files have a lot of use statements.

As a programmer
I'd like to collapse the use statements
to reduce noise, when working on my code.

Please add a possibility to collapse use statements like you can collpase functions.

PS: Maybe a different issue, but collapsing crates would be nice, too.

[matklad]

If anyone wants to look into this, the code is in https://github.com/intellij-rust/intellij-rust/blob/master/src/main/kotlin/org/rust/ide/folding/RsFoldingBuilder.kt.

[framlog]

I'm going to do this.

[Undin]

Implemented in #2101