Update to Gradle 9.5.0

[rvandermeulen]

Updates Gradle from 8.14.3 to 9.5.0, and moves off the APIs that AGP 9 removes while staying on AGP 8.

9.5.0 is as far as we can go for now: Gradle 9.6.0 removes org.gradle.api.problems.internal.InternalProblems, which AGP 8.x's com.android.internal.library depends on, and 8.13.2 is the last AGP 8 release. Going further requires the AGP 9 upgrade, which is deliberately not part of this.

Breaking change for consumers of the Glean Gradle plugin. Gradle 9 removed Project.exec(), which JetBrains' gradle-python-envs calls internally. That plugin is unmaintained, 0.0.31 is its only recent release, and there is no Gradle 9 compatible version, so the Miniconda bootstrap is gone. The plugin now always creates a virtual environment with the standard library venv module, which is the path that already existed for offline builds. Applications need a Python 3.9 or later interpreter on the PATH, or GLEAN_PYTHON set, unless they supply their own environment via ext.gleanPythonEnvDir. They no longer need to apply com.jetbrains.python.envs themselves.

Note that on Debian and Ubuntu this also means python3-venv has to be installed, since a bare python3 there has no ensurepip. That is what the first commit does for our own Android CI jobs, and downstream consumers building on similar images will need the same. mozilla-central already sets gleanPythonEnvDir everywhere, so it is unaffected.

The rest of the stack prepares for AGP 9. Registering the uniffi bindings through androidComponents also let the lint baseline go away: the generated directory was being added to the Kotlin source set by hand, which is why lint treated the bindings as ordinary source and needed three NewApi suppressions.

Along the way this fixes three latent missing task dependencies, all of which had been masked by warm build directories and scheduling that happened to work:

• copyGleanNative could copy the native libraries before Cargo had built them
• the metrics generating tasks could run before the Python environment existed
• the Maven artifact check ran before publish, found nothing, and passed

The last one is worth a second look: bin/check-artifact.sh treated "no artifact found" as success, so the release check in module-build would have gone green while verifying nothing. It now fails instead of skipping whenever it has nothing to inspect.

These were all found while trying to enable the configuration cache, which is not part of this PR. That turned up a problem outside this repo: with the cache on, a consumer task with a correct dependsOn on rust-android-gradle's cargo task still observes an empty output directory on a cold build, which suggests the plugin does not declare rustJniLibs in a way Gradle's parallel scheduler respects. The compatibility fixes are kept here since they are improvements in their own right, and enabling the cache can be revisited once that is sorted out.

Verified on a clean tree with a cold Python environment: full build, all three unit test variants, detekt, ktlint, offline builds, publishing, and the module-build and android-build CI task sequences.

Not covered: Windows, where the interpreter path changed from the conda layout to Scripts/python.