alternative to postfix `ifl` completion that matches `Err` for `Result`

Currently we have ifl as a way to expand <expr of type Result<_,_>>.ifl to

if let Ok(<cursor>) = <expr of type Result<_,_>> {

}

But I find myself regular wanting to match on Err rather than Ok.

i.e. have e.g. ifle that expands <expr of type Result<_,_>>.ifle to

if let Err(<cursor>) = <expr of type Result<_,_>> {

}

Alternatively to adding a new postfix expansion keyword if possible the ifl could also ask for which variant one wants to match on instead of assuming Ok for Result.

Start by locating the postfix completion implementation for the existing ifl expansion in rust-analyzer. Compare the current Result/Ok behavior with the requested Err variant, then verify that either an ifle expansion or variant-selection prompt produces the expected Rust snippet.