src: inline AsyncCleanupHookHandle in headers
Fixes: https://github.com/nodejs/node/issues/36349
It doesn't look like there is any documentation for this feature as of yet, since it seems to be experimental (and I might be the only user of it), so I didn't need to do anything for documentation. Testing covers this area in both N-API and for regular addons. Having trouble Running the InspectorSocketServerTest
locally, but was able to dig through the makefile to find a test target for the affected work.
@addaleax Pinging you as requested. Thank you for all your help!