[➕ Feature]: Backend pagination for alerts endpoints

[Kiryous]

Is your feature request related to a problem? Please describe. Currently all alerts for the preset are present in the response. For 600 alerts it takes ~1.5s to get it.

Describe the solution you'd like Let's use the same approach as with incidents for pagination of alerts

[ohadch]

Hey, I'll be happy to work on this PR. Can I be assigned? :)

[talboren]

@ohadch it'll be amazing to see you contributing here! assigned :)

[ohadch]

Thanks @talboren !

[VladimirFilonov]

Hello, @ohadch! Any progress on this one? =)

[Matvey-Kuk]

I think it's not relevant anymore since @skynetigor refactored most of the backend there.