Teach the flutter tool how to find android output files if the flavor contains uppercase letters

[knaeckeKami]

Description

This changes the name of the generated output files on android in case a flavor with uppercase letters is used.
Previously, the lowercased flavor name would be used for the apk/aab file. Now, the flavor name is used as-is.

Example: when adding a flavor with the name "aB" to the flutter template project, the name of the generated .aab file is now

app-aB-release.aab instead of
app-ab-release.aab

Because of calling .toLowerCase() on the flavor name, the generated apk/aab files would not be found after the Gradle build for users that use a case sensitive file system (typically Linux, but not Windows or Mac OS), and they would get an error message

Gradle build failed to produce a .apk file. It's likely that this file was generated under /builds/<...>/build, but the tool couldn't find it.

because the flutter tool looks for a file with the real flavor name in its name, not the lowercased flavor name.
See https://github.com/flutter/flutter/blob/master/packages/flutter_tools/lib/src/android/gradle.dart#L900

Related Issues

fixes #24106 , particularly #24106 (comment)

Tests

I did not add tests. Since this is a change in the gradle file for the android build process, I don't know how I would add a test for this. If tests are required, I would appreciate a pointer on how and where to add them.

Checklist

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Breaking Change

Did any tests fail when you ran them? Please read [Handling breaking changes].

• Yes, this is a breaking change. If not, delete the remainder of this section.
  • I wrote a design doc: https://flutter.dev/go/template Replace this with a link to your design doc's short link
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• No, no existing tests failed, so this is not a breaking change.

This should not be a breaking change.
If one does not use uppercase letters in flavor names, nothing changes.

Otherwise, for Windows and Mac, this name of the generated file apk will be different, however, since the file systems of these operating systems are not case sensitive, this should not cause problems.
On Linux, this should also not be a breaking change, since using a flavor name with uppercase letters caused the build to fail anyway previously.

Alternatives

If using upper case letters in the output files is not desired, we could also fix the expected file names in
https://github.com/flutter/flutter/blob/master/packages/flutter_tools/lib/src/android/gradle.dart to use the lower case flavor names.

see #65768

[jonahwilliams]

LGTM

[knaeckeKami]

Hm, do you have an idea why deploy_gallery-macos still fails?

[jonahwilliams]

flaky test, I restarted it