[camera] Remove OCMock from tests

[mchudy]

This PR removes dependency on OCMock in unit tests and serves as a first step for full Swift migration. flutter/flutter#119109

• Introduces wrapper protocols around AVFoundation class with default implementations and mocks
• Replaces usages of AVFoundation classes with new protocols
• Refactors dependency injection with FLTCamConfiguration for easier usage in tests as new protocols increased the number of dependencies required to initialize a new FLTCam instance
• I tried to minimize changes to FLTCam to minimize the risk of introducing regressions. Splitting FLTCam into smaller classes will happen in further PRs.
• Relying on the new protocols in some cases is cumbersome because AVFoundation methods require pointers to raw objects thus I'm sometimes keeping the underlying instance exposed which is not very elegant, I'm open to any suggestions on to how we can clean this up.

I took some inspiration from how it was done in case of the in_app_purchase package flutter/flutter#116383

Pre-launch Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• I read the Tree Hygiene page, which explains my responsibilities.
• I read and followed the relevant style guides and ran the auto-formatter. (Unlike the flutter/flutter repo, the flutter/packages repo does use dart format.)
• I signed the CLA.
• The title of the PR starts with the name of the package surrounded by square brackets, e.g. [shared_preferences]
• I linked to at least one issue that this PR fixes in the description above.
• I updated pubspec.yaml with an appropriate new version according to the pub versioning philosophy, or this PR is exempt from version changes.
• I updated CHANGELOG.md to add a description of the change, following repository CHANGELOG style, or this PR is exempt from CHANGELOG changes.
• I updated/added relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or this PR is test-exempt.
• All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel on Discord.

[hellohuanlin]

Thank you for your contribution! I'm very excited about this change!

It's pretty hard to review a 3000+ LOC PR. Could you break it down to smaller pieces? Smaller PR also helps with resolving potential code conflict since this plugin is being actively developed by the community.

[hellohuanlin]

is minimum SDK bump related to OCMock removal?