Medical - Allow scripted damage on dead units

[SpicyBagpipes]

When merged this pull request will:

• title

IMPORTANT

• If the contribution affects the documentation, please include your changes in this pull request so the documentation will appear on the website.
• Development Guidelines are read, understood and applied.
• Title of this PR uses our standard template Component - Add|Fix|Improve|Change|Make|Remove {changes}.

[PabstMirror]

means you can backblast//overpressure dead units, but I don't see how that would cause any problems

ace_fire avoided using this func because of the limitation, so I guess it could switch to it but it's fine as is

Use event directly, as ace_medical_fnc_addDamageToUnit requires unit to be alive