update code-checkers config

[sergei-solonitcyn]

Signed-off-by: Sergei Solonitcyn [email protected]

What

Connectors' code quality tools used by invoke commands required some improvements:

• all-checks tasks run only first task in its list
• mypy missed stubs
• mypy used cache, but it's not desirable for our purposes
• mypy didn't use implicit reexport
• several sequenced tasks in all-checks or coverage weren't splitted in any way

How

• Run all-checks tasks inside try-except blocks, as it's done in coverage
• Add a command for installing mypy stubs
• Update mypy config section