[theory]

It has not been possible, up to now, to query the server to determine whether chdb_hook is installed, although the presence of chdb in pg_available_extensions is a fine substitute. But it can be useful to make chdb_hook available there, too.

So add chdb_hook.control so it can be listed in
pg_available_extensions and added to a database via CREATE EXTENSION chdb_hook. Add the chdb_hook_version() function so that there's a handle one can use to load the module after creating the extension, effectively the same as LOAD, but with the advantage of supplying the version, as well.

Refactor the Makefile to support both extensions, so that it creates sql/chdb_hook-$VERSION.sql and installs it. Add EXT_NAME as the package name, chdb, since EXTENSION now includes the names of both extensions.

Document this functionality in chdb_hook.md, including how to load the module via the extension objects. But recommend loading the module in session_preload_libraries.

Modify the extension.sql test to load both extensions and compare their versions, both the full x.y.z version of the modules as well as the x.y versions of the extensions.