☂️ Gradle 8.7, AGP 8.4, Java 21, support

[reidbaker]

Goals:

• Fix Cannot invoke method exec() on null object occured at flutter.groovy:1041 (Add to App Project, AGP 8.x.x) #138523 and any other doLast block issues
• Update at least some of our own infra to use gradle 8.7, agp 8.4 and java 21.

[bartekpacia]

Out of curiostiy: any reason for Gradle 8.4 specifically? Latest is 8.7.

[gmackall]

I think in practice this will be Gradle 8.6+, as it seems like AGP 8.4 requires that
https://developer.android.com/build/releases/gradle-plugin

[reidbaker]

@bartekpacia just a typo, title and body updated.

[bartekpacia]

I think you meant Gradle 8.7, not AGP 8.7 ;-) I changed it again.

[flutter-triage-bot]

This issue is assigned to @gmackall but has had no recent status updates. Please consider unassigning this issue if it is not going to be addressed in the near future. This allows people to have a clearer picture of what work is actually planned. Thanks!

[gmackall]

Still working on tasks related to this, ex flutter/packages#7432