reviewed by kb

after the user presses Expand All in Usages view, subsequent usage searches are shown as always expanded (IDEA-82552)
(cherry picked from commit fb286097)

(cherry picked from commit ea49ecf4)
(cherry picked from commit 75ed5963)

(cherry picked from commit 32fa8b7d)

(cherry picked from commit ac06c394)

(cherry picked from commit 0eb3de27)

(cherry picked from commit 0fdf921b)

(cherry picked from commit 36bacc05) [cdr]

use correct language level when creating name identifiers for renamed elements (EA-43620 - CCE: PyElementGeneratorImpl.createNameIdentifier)

fix CSS completion tests: if the reference starts at completion start location, we do need to overwrite it when Tab is pressed

consistent behavior of PyFunction.getContainingClass() in stub-based and non-stub-based cases (PY-1448)

if there are two existing import statements that import from the same file, don't show two same items in import popup (PY-9138)

allow "create class" fix for names which start with multiple uppercase characters but aren't entirely uppercase (PY-7423)