Support Health Checks for Azure functions package

[vany0114]

According to the documentation the health checks is a built-in feature but it seems to be this is not working/included in the apollo-server-azure-functions package.

I can help with this if you guys want it.

[glasser]

You're correct: that package doesn't implement that feature. I'd be happy to merge a PR that implements it; it shouldn't be too hard to borrow an implementation from the Lambda package or something.

[trevor-scheer]

Looks like a fix for this landed in #5003