biosig: use tinyxml2

[scpeters]

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Split out from #119829.

[p-linnane]

Awesome, thanks @scpeters!

[scpeters]

rarian build works on macOS but fails on Linux

[p-linnane]

Rerunning with no-fail-fast so we can see everything and debug from there.

[scpeters]

rarian build works on macOS but fails on Linux

ok, I was wrong about rarian. I was testing on my local machine that still had tinyxml installed and linked in the background. Unlinking tinyxml shows the same failure. I'll redact rarian from this PR, since I think biosig does still work

[github-actions]

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