keyword: Tests for `softkwlist`

[Eclips4]

In 3.10 version python have introduced new type of keywords such as soft.
There's no tests for it, so i decided to write it =)
Follows issue at typeshed about typehints of kwlist & softkwlist, we have came to conclusion to use assertSequenceEqual in test_keywords_are_sorted instead of assertListEqual.

Linked PRs

• gh-102158: Add tests for softkwlist #102159
• [3.11] gh-102158: Add tests for softkwlist (GH-102159) #102198
• [3.10] gh-102158: Add tests for softkwlist (GH-102159) #102199