feat(extensions.postgresql). Support for extension version upgrade

[petteja]

What problem are you facing?

There is currently no way to upgrade extension version

How could Crossplane help solve your problem?

Upgrade the extension to the version specified by the crd

[chlunde]

A good start would be to expose the installed and default version in status.atProvider

SELECT oid, extname, extversion FROM pg_extension;
SELECT name, default_version, installed_version 
  FROM pg_available_extensions;


ALTER EXTENSION extension_name UPDATE TO 'new_version';