multiple small fixes to the backend

[paskal]

• regenerate mocks, so that go generate doesn't produce difference for the users
• use require.NoError(t, err) in place of requre.Nil(t, err) for consistency
• extract TelegramBotInfo structure, as it will be reused later on in the notifications subscription code

[coveralls]

Pull Request Test Coverage Report for Build 1383050148

• 2 of 2 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.03%) to 83.827%

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Totals
Change from base Build 1378472731:	0.03%
Covered Lines:	5831
Relevant Lines:	6956

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💛 - Coveralls