Move the injection_points extension to contrib?

Are there any objections against $SUBJECT?

Having the extension in contrib would be useful in cases a 3rd party extension
uses injection points in its regression tests. In particular, it's more
practical for CI to install the "injection_points" extension by installing the
"contrib" binary package than by building the whole server from source. (AFAIK
the src/modules/injection_points directory is currently not included in any
package.)

-- 
Antonin Houska
Web: https://www.cybertec-postgresql.com