Better error reporting for duplicated fields anonymous record expressions

[edgarfgp]

Continuation of #15824

[T-Gro]

Does the behavior affect also:

• with copy-and-update syntax ?
• anonymous records used in type annotations ?

What I am unsure after this change is whether there is a situation in which an error would be doubled.

[edgarfgp]

• with copy-and-update syntax ?

It won't affect the with copy-and-update syntax we are still using error so we won't cascade errors (See the tests for more info)

• What I am unsure of after this change is whether there is a situation in which an error would be doubled.

I double-checked with the CopyAndUpdateTests and it seems fine to me

fsharp/tests/FSharp.Compiler.ComponentTests/Language/CopyAndUpdateTests.fs

Line 4 in 9df89d2

open FSharp.Test.Compiler