Backslash in {js||js} throws exception

[IwanKaramazow]

let x = {js|\ |js}
(* rescript *)
let x = `\ `

The example throws invalid escape code. Should we follow the exact same behaviour as JS?

Related: https://forum.rescript-lang.org/t/syntax-to-break-long-single-line-strings/

[IwanKaramazow]

On further thought, maybe this should be handled in the surface syntax

[IwanKaramazow]

rescript-lang/syntax#118 handled in the parser