Fix overloads and unlock mypy on tests

[beliaev-maksim]

• added typing in tests
• reverted overloads for activate
• Fix matchers typing
• Added status and body attributes to BaseResponse

closes #692

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (c46cb06) 99.50% compared to head (6a492e8) 99.50%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #694 +/- ## ======================================= Coverage 99.50% 99.50% ======================================= Files 9 9 Lines 3044 3053 +9 ======================================= + Hits 3029 3038 +9 Misses 15 15 ```

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