Swiftlint fixes & configuration changes; Make GestureManager.delegate weak

[macdrevx]

Pull request checklist:

• Briefly describe the changes in this PR.
• Document any changes to public APIs.
• Apply changelog label ('breaking change', 'bug 🪲', 'build', 'docs', 'feature 🍏', 'performance ⚡', 'testing 💯') or use the label 'skip changelog'
• Add an entry inside this element for inclusion in the mapbox-maps-ios changelog: <changelog>Breaking: GestureManager.delegate is now weak</changelog>.

Summary of changes

• Migrated swiftlint config to use opt_in_rules and disabled_rules so that we can more easily discover new rules as they are added.
• Updated swiftlint excludes for new source layout
• Autocorrected various lint violations
• Corrected GestureManager.delegate weak delegate violation
• Disabled trailing_comma rule since we'd need to wrap closing array braces consistently for it to make sense
• Added swiftlint:disable commands to ignore other lint warnings
• Added a child config for the Tests directory that is slightly more permissive.
• Run swiftlint in CI directly rather than depending on it running as a build phase. This will be helpful as we migrate to SPM-based builds in CI.
• Run swiftlint in strict mode in CI. This should fail builds that have lint so that we don't regress.

[julianrex]

LGTM

[neelmistry94]

One open question, nothing that prevents me from approving