Reduce noise in signatures of compiled params (#1564)

* Remove "typing." prefix from compiled signature param

* Don't print default "None" for Optional params

* Don't remove 'typing.' prefix if symbol doesn't come from typing module

* Revert "Don't print default "None" for Optional params"

This reverts commit 8db334d9bb.

* Make sure "typing." doesn't appear in the middle

* Make sure only "typing." prefix is removed and not it's entries in the middle

* Use inspect.formatannotation() to create an annotation string

* Update AUTHORS.txt

* Add test for compiled param annotation string

* Replace Optional in test with other typing facilities

in order for test to be forward-compatible with 3.9

* Add an empty string fallback for Python 2

* Move _annotation_to_str back to original position

AUTHORS.txt

@@ -58,6 +58,7 @@ Code Contributors
 - Lior Goldberg (@goldberglior)
 - Ryan Clary (@mrclary)
 - Max Mäusezahl (@mmaeusezahl) <maxmaeusezahl@googlemail.com>
+- Vladislav Serebrennikov (@endilll)
 
 And a few more "anonymous" contributors.