Enums are always read-only (#7434)
Enums are always read-only (#7434)

* Enums are always read-only

* Minor cleanup

dsyme/fsharp,dsyme/fsharp,dsyme/fsharp,cloudRoutine/FSharp.Compiler.Service,cloudRoutine/FSharp.Compiler.Service,cloudRoutine/FSharp.Compiler.Service,dsyme/fsharp,dsyme/fsharp,dsyme/fsharp,dsyme/fsharp