[lthooks] Reorder generic hook names

[PhelypeOleinik]

Brief outline of the enhancement

When developing lthooks we ended up with generic hooks named in two different ways: with the variable part in the second position as in env/<name>/before, and in the end, as in file/before/<name>. This difference makes it difficult to remember which is which, and makes for unnecessary complication in the code.

The plan here is to change all generic hooks to have the variable part in the second position in the name, so these hooks will be changed (hoping I didn't forget any):

Old name	New name
file/before/<file>	file/<file>/before
file/after/<file>	file/<file>/after
package/before/<package>	package/<package>/before
package/after/<package>	package/<package>/after
class/before/<class>	class/<class>/before
class/after/<class>	class/<class>/after
include/before/<file>	include/<file>/before
include/end/<file>	include/<file>/end
include/after/<file>	include/<file>/after

A deprecation cycle will be provided so that the old names still work for some time, to allow adjustments without compatibility issues.