Fix 11873: Name is bound multiple times is not reported in 'as' pattern

[edgarfgp]

Description

Fixes #11873

Before

let f1 a a = ()
         ^
         Error: "'a' is bound twice in this pattern"
let f2 (a, b as c) c = ()
				   ^
				   Error: "'c' is bound twice in this pattern"

let f3 (a, b as c) a = ()
				   ^
				   No Error

After

let f1 a a = ()
         ^
         Error: "'a' is bound twice in this pattern"
let f2 (a, b as c) c = ()
				   ^
				   Error: "'c' is bound twice in this pattern"

let f3 (a, b as c) a = ()
				   ^
				   Error: "'a' is bound twice in this pattern"

Checklist

• Test cases added
• Release notes entry updated

[github-actions]

❗ Release notes required

---

✅ Found changes and release notes in following paths:

Change path	Release notes path	Description
src/Compiler	docs/release-notes/.FSharp.Compiler.Service/11.0.0.md

[edgarfgp]

This is ready