Update all plugins that use verifyToken to use verify instead

[collinjackson]

#4640 (reviewed by @stuartmorgan) updated plugin_plugin_interface to 2.1.0, soft-deprecating verifyToken and introducing its replacement, verify.

Now that 2.1.0 has been published, this PR updates all of the first-party plugins that used verifyToken to use verify and depend on ^2.1.0:

• camera
• file_selector
• google_maps_flutter
• image_picker
• in_app_purchase
• path_provider
• quick_actions
• url_launcher
• video_player
• webview_flutter

It is a follow-on fix for flutter/flutter#96178

Test plan

This PR has no new tests because it's not possible to test; there was no semantic change to the above plugins. They are not using const Object() as their token so a test cannot cause the new AssertionError to be thrown. I believe this means @Hixie has to sign off on it and I've posted in #hackers-ecosystem about that.

However, this PR does contain new tests in the sense that there are new tests in #4640 and this is a follow-on PR that could only be landed after that one did because of the plugin_platform_interface dependency. In some sense this repo is a giant test case and we're testing #4640 by creating lots of sample apps that depend on it.

Pre-launch Checklist

• I read the [Contributor Guide] and followed the process outlined there for submitting PRs.
• I read the [Tree Hygiene] wiki 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/plugins repo does use dart format.)
• I signed the [CLA].
• [too many plugins to list] The title of the PR starts with the name of the plugin surrounded by square brackets, e.g. [shared_preferences]
• I listed 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].
• I updated/added relevant documentation (doc comments with ///).
• [need approval] I added new tests to check the change I am making, or this PR is [test-exempt].
• All existing and new tests are passing.

[flutter-dashboard]

It looks like this pull request may not have tests. Please make sure to add tests before merging. If you need an exemption to this rule, contact Hixie on the #hackers channel in Chat.

If you are not sure if you need tests, consider this rule of thumb: the purpose of a test is to make sure someone doesn't accidentally revert the fix. Ask yourself, is there anything in your PR that you feel it is important we not accidentally revert back to how it was before your fix?

Reviewers: Read the Tree Hygiene page and make sure this patch meets those guidelines before LGTMing.

[stuartmorgan-g]

LG other than version issue

[stuartmorgan-g]

Since the final version of the platform interface chance doesn't require any breaking changes (the deprecation after this all lands is just a minor bump per semver and standard Dart package practice), these should all be ^2.1.0 instead.

[collinjackson]

That is what I had in a previous version of this PR, and I've reverted back to it.

[stuartmorgan-g]

LGTM. Thanks for doing all this cleanup!

[Hixie]

test-exempt: code refactor with no semantic change

[fluttergithubbot]

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[ditman]

Thanks for the cleanup @collinjackson! Long time no see!