fix: added revertFlutterImage call in integration_tests

[YukiAttano]

Implemented the Integration test function "revertFlutterImage()* that is missing for 3 years.

Edit:
To add some context:
The "IntegrationTestWidgetsFlutterBinding" Class provides a function called "takeScreenshot".
This function requires to call "convertFlutterSurfaceToImage" on Android devices to work.
That function states in it's documentation that you have to call "revertFlutterImage", after taking a screenshot, to further use your integration test.
The mentioned function was never publicly available but used only in the "addTeadDown" callback.

This PR adds the missing "revertFlutterImage" as a call to the API for people to use in their integration tests.

Issue List

• Missing revertFlutterImage function in integration_test #92381

Pre-launch Checklist

• [X ] I read the [Contributor Guide] and followed the process outlined there for submitting PRs.
• [ X] I read the [Tree Hygiene] wiki page, which explains my responsibilities.
• [ X] I read and followed the [Flutter Style Guide], including [Features we expect every widget to implement].
• [ X] I signed the [CLA].
• [ X] I listed at least one issue that this PR fixes in the description above.
• [ X] I updated/added relevant documentation (doc comments with ///).
• [ X] I added new tests to check the change I am making, or this PR is [test-exempt].
• [ X] All existing and new tests are passing.

[johnmccutchan]

I think you should fix takeScreenshot to do the right thing and not extend the API surface area.

[YukiAttano]

@johnmccutchan that is indeed a point. It would be far simpler for any user if that function would do everything that is required to get that screenshot.
For now i have only provided the missing function that was mentioned years ago and people expect to be there.
Because everything here has to have an Issue first, i think your idea is then more of a feature request that needs to be addressed separately.
I'll try to follow the guidelines here, as my implemented function is already mentioned by the api, i wouldn't consider this an extension of the api surface whereas your good idea would be a "breaking change".

According to the existing function documentation, it is not possible to do it like you suggested.
From IntegrationTestWidgetsFlutterBinding.takeScreenshot()

On Android, you need to call convertFlutterSurfaceToImage(), and pump a frame before taking a screenshot.

That pumping is made in the WidgetTester class which seems to be out of scope of the Binding class, as i suppose.

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