Remove unused code

[nojaf]

In light of #14567, I believe to have found some code that is unused.

These are top-level functions that are unused in the file they are defined and are not part of the signature.

In some cases, I did update the signature file. (For example in Result.toSeq in FSharp.Core, because the value was missing in src/FSharp.Core/result.fsi it was considered unused).

And in sformat.fs I did shuffle some functions a bit because depending on the COMPILER define value the code was considered to be unused or not. This file is used both in FCS and FSharp.Core.

[KevinRansom]

I love this change, but I want to understand whether the reordering of the baseline file is benign.
Also there is too much churn in that file to see whether something interesting was removed.

So if we can hold off on merging for a short while.

[T-Gro]

I want to nominate this for PR of the year.

[KevinRansom]

I'm gonna do the baselines for this differently, so the big delta here is fine for now.

[KevinRansom]

Now I think I understand what is going on with the baseline.

[nojaf]

@T-Gro I've addressed all the remarks. This one is good to go.