Add benchmark data for testing non-vectorised paths

[Gnbrkm41]

Related: dotnet/coreclr#27798

The first commit is related to the PR mentioned above; I think it could be worth adding this even if the PR above doesn't make it in, in case there could be a similar change.

The second commit is per dotnet/corefx#39173 (comment).

[adamsitnik]

LGTM, thank you!

[Gnbrkm41]

I'll need to add some more cases to follow up with changed implementations.

[adamsitnik]

I'll need to add some more cases to follow up with changed implementations.

Please tag me when the PR is ready to merge (I would prefer to merge 1 final PR)

[Gnbrkm41]

Is the performance repo being merged into runtime or somewhere else as well? Thought this was going to stay.

[adamsitnik]

Is the performance repo being merged into runtime or somewhere else as well?

No. It's going to stay as it is today (and this time the fact that it's a standalone repo is going to save us a lot of time an engineering effort ;) )

[Gnbrkm41]

Actually... I think this is good as-is. I was going to add a slightly longer string, thinking it would matter since I changed the implementation to process more at once; but it is covered by the current data as well. @adamsitnik should be good now.