Migrates the camera plugin to the new embedding and adds an example
activity exercising it.

Unlike some of the previous PRs on this, this is the minimal migration
that would land this without adding any tech debt. From previous offline
discussions we'd like to scope these migrations to the bare minimum
required to keep the patches small. See #2114 for a migration combined
with a refactoring.

That said there are still some minor changes to prevent this from adding
additional tech debt, going a little beyond #2118:

- `#onMethodCall` has been split up into its own `MethodCallHandlerImpl`
class to try and keep `CameraPlugin` from mixing concerns. Before the
migration, _all_ it was doing was responding to method calls. Now
there's a significant amount of logic just based around responding to
lifecycle events. It still seemed better to split that into a separate
file than to try and manage that logic all in one place.

Other than the above refactor, the original logic is untouched.

Migrates the camera plugin to the new embedding and adds an example
activity exercising it.

Unlike some of the previous PRs on this, this is the minimal migration
that would land this without adding any tech debt. From previous offline
discussions we'd like to scope these migrations to the bare minimum
required to keep the patches small. See flutter#2114 for a migration combined
with a refactoring.

That said there are still some minor changes to prevent this from adding
additional tech debt, going a little beyond flutter#2118:

- `#onMethodCall` has been split up into its own `MethodCallHandlerImpl`
class to try and keep `CameraPlugin` from mixing concerns. Before the
migration, _all_ it was doing was responding to method calls. Now
there's a significant amount of logic just based around responding to
lifecycle events. It still seemed better to split that into a separate
file than to try and manage that logic all in one place.

Other than the above refactor, the original logic is untouched.

Migrates the camera plugin to the new embedding and adds an example
activity exercising it.

Unlike some of the previous PRs on this, this is the minimal migration
that would land this without adding any tech debt. From previous offline
discussions we'd like to scope these migrations to the bare minimum
required to keep the patches small. See flutter#2114 for a migration combined
with a refactoring.

That said there are still some minor changes to prevent this from adding
additional tech debt, going a little beyond flutter#2118:

- `#onMethodCall` has been split up into its own `MethodCallHandlerImpl`
class to try and keep `CameraPlugin` from mixing concerns. Before the
migration, _all_ it was doing was responding to method calls. Now
there's a significant amount of logic just based around responding to
lifecycle events. It still seemed better to split that into a separate
file than to try and manage that logic all in one place.

Other than the above refactor, the original logic is untouched.

Migrates the camera plugin to the new embedding and adds an example
activity exercising it.

Unlike some of the previous PRs on this, this is the minimal migration
that would land this without adding any tech debt. From previous offline
discussions we'd like to scope these migrations to the bare minimum
required to keep the patches small. See flutter#2114 for a migration combined
with a refactoring.

That said there are still some minor changes to prevent this from adding
additional tech debt, going a little beyond flutter#2118:

- `#onMethodCall` has been split up into its own `MethodCallHandlerImpl`
class to try and keep `CameraPlugin` from mixing concerns. Before the
migration, _all_ it was doing was responding to method calls. Now
there's a significant amount of logic just based around responding to
lifecycle events. It still seemed better to split that into a separate
file than to try and manage that logic all in one place.

Other than the above refactor, the original logic is untouched.