feat: Expand flame_lint to respect required pub.dev checks

[luanpotter]

Description

Expand flame_lint to respect required pub.dev checks.

We are currently losing pub points due to lint violations:

Turns out flame_lint does not respect lints/core which is being enforced now by pub.

This adds that as a dependency on flame_lint, updates flutter_lint for the packages that use that, and fix all existing violations (luckily very few).

This change will ensure that us and everyone else who uses flame_lint get all the points they deserve on pub. We can consider expanding to lints/recommended in the future, but that is definitely not a requirement at this stage (and a much bigger change).

Checklist

• I have followed the Contributor Guide when preparing my PR.
• I have updated/added tests for ALL new/updated/fixed functionality.
• I have updated/added relevant documentation in docs and added dartdoc comments with ///.
• I have updated/added relevant examples in examples or docs.

Breaking Change?

• Yes, this PR is a breaking change.
• No, this PR is not a breaking change.