feat(bloc_lint): avoid_returning_new_instance_from_bloc_provider_value

[felangel]

Description

As a developer, I want to be warned if BlocProvider.value creates a new bloc instance (originally referenced in #4264)

[faheemabbas766]

Hi @felangel , I’d like to work on this rule. I verified that it is not currently implemented and couldn’t find a matching open PR.

My proposed scope is to report direct Bloc/Cubit construction in BlocProvider.value, while avoiding arbitrary function calls to minimize false positives. I’ll include focused positive/negative tests, rule registration, documentation, and a changelog entry. Is this scope still desired?