Show the actual type of RHS on type error when LHS is a pattern with a type annotation

[travv0]

Description

Previously, when a pattern on the LHS had a type annotation that didn't match the binding's type, a type error would report the annotation type as the type of the RHS. This PR separates it into two steps, so the binding type is checked against the annotation type, and then the RHS's type is checked against the binding's type. (Hopefully I worded this okay, I'm new to typechecking stuff.)

Fixes #18849

Checklist

• Test cases added

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[github-actions]

❗ Release notes required

@travv0,

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Change path	Release notes path	Description
src/Compiler	docs/release-notes/.FSharp.Compiler.Service/10.0.300.md	No release notes found or release notes format is not correct