feat: Full support of AGP 8

[vbuberen]

Description

This PR is a replacement for #11318 as it was agreed in that PR. Opened another PR as don't have access to push anything to that other fork used to create #11318.

Summary of changes and things to note:

• Added required buildFeatures block in all build.gradle files for support of AGP 8.
• Dropped step to install Java from CI as it is pre-installed on Github runners: https://github.com/actions/runner-images/blob/main/images/linux/Ubuntu2204-Readme.md UPD: Looks like workflow can't pick Java 17 on its own even though it is installed, so brought back the Java setup step.
• Dropped Jetifier everywhere as it is not needed and negatively influences build speed: https://adambennett.dev/2020/08/disabling-jetifier/
• Switched to new syntax to declare min, target and compile SDKs (e.g. instead of compileSdkVersion use compileSDK). Note, this would require projects using plugins to have at least AGP 7 as it mentioned here: https://developer.android.com/about/versions/13/setup-sdk
• Updated AGP everywhere to 8.1.2 and Gradle wrapper to 8.3. Considering that some plugins still had 3.x versions of AGP after this PR build speed should improve for such packages.
• Bumped minSDK to 19 for all plugins, because with current min Flutter version 19 is minimally supported anyway: https://docs.flutter.dev/reference/supported-platforms#deploying-flutter
• Dropped last mentions of jcenter() as it is not reliable and replaced with mavenCentral().
• Changed declaration of Kotlin dependency to not mention -jdk7 or -jdk8 as it is not needed for quite a long time already and since release 1.8.x is the default required way of declaring Kotlin dependency.
• I didn't update Kotlin as it was done in that other PR, because it would bring only issues to most projects. See [Bug]: Android build failures fluttercommunity/plus_plugins#2251 and Build failed when updating to latest version juliansteenbakker/mobile_scanner#729 for more information on the issue.
• Updated annotation Android dependency in all plugins.
• Removed redundant gradle folders in packages where they are not needed.
• Did some formatting for build.gradle files so they have the same position of blocks across plugins as it was confusing to update code in different places for every plugin.

Related Issues

Closes #11266

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Breaking Change

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[vbuberen]

@russellwheatley Here it is, the updated version of #11318

I would also appreciate if you review #11671 as well.

[russellwheatley]

@vbuberen - thank you for the PRs 🥳 . I will take a look at them next week 😄

[russellwheatley]

@vbuberen - The CI is failing because of the need for compileSdkVersion here: https://github.com/firebase/flutterfire/actions/runs/6533992367/job/17740279394?pr=11699#step:14:62

I've built it locally and it doesn't work with compileSDK but does build with compileSdkVersion 🤔

[vbuberen]

I've built it locally and it doesn't work with compileSDK but does build with compileSdkVersion 🤔

I will check it out a bit later today.

[vbuberen]

I made a typo there 🤦🏻
It should be compileSdk not compileSDK

[russellwheatley]

Great work, @vbuberen 🥳