Keeping error context for tuple length mismatch

[0101]

Followup for #13347

When a tuple length mismatch happens within a situation where we keep additional context, we show a context-aware error message. E.g.

let f1(a, b: string, c) =
    if true then (1, 2) else (a, b, c)

All branches of an 'if' expression must return values implicitly convertible to the type of the first branch, which here is a tuple of length 2 of type
    int * int    
This branch returns a tuple of length 3 of type
    'a * string * 'b 

[T-Gro]

Can we merge here or is it still waiting?
IMO this is already an improvement for the "Simple F#" theme.

[0101]

@T-Gro this can be merged after it's reviewed.

[abonie]

Looks like a great step towards better compiler error messages 👍