[Core] Quiet hours for a health check

[blackandred]

Given I have expected failure of a health check at given time ex. increased load average in nightly hours during backup packaging
Then I expect that my health check will not raise alert during that hours

{
    "quietHours": [
        {"from": 7, "to": 10},
        {"from": 4, "to": 6}
    ]
}