refactor!: comet_info to struct

[tac0turtle]

Description

this pr pulls out core changes to a separate pr and makes the entire comet core a struct

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• included the correct type prefix in the PR title
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[testinginprod]

I generally agree with the direction, Comet is a specialised service (works only when consensus engine is Comet) so we don't need more abstractions, there's always going to be one Comet service implementation.

[julienrbrt]

Can we add a breaking change changelog to core?