Merge: Annotation lateinit

Merge: Annotation lateinit

#857 introduced `autoinit` on attributes that has a default value to initialize them latter.

This is a rarely used feature. It is also not POLA because it overloads the name `autoinit` that has a different meaning on methods cf #1308.

Thus in order to polaize the spec, the annotation is renamed `lateinit`. So close #1308.
Note: maybe the annotation will just be removed in a future PR, this one is a last attempt to keep it.

Related to #1322; required by #1311

Pull-Request: #1409
Reviewed-by: Alexandre Terrasa <alexandre@moz-code.org>
Reviewed-by: Lucas Bajolet <r4pass@hotmail.com>
Reviewed-by: Romain Chanoir <chanoir.romain@courrier.uqam.ca>