flutter_tools: Enable native access for Gradle - #193814

JDK 24 (JEP 472) prints a warning when particular JNI/FFM methods such
as `System::load` are called unless it has been granted native access
via a flag or jar manifest. Gradle loads its native-platform library
this way, so we get the following warnings on every Gradle invocation on
JDK 24 and later:

  WARNING: A restricted method in java.lang.System has been called
WARNING: java.lang.System::load has been called by
net.rubygrapefruit.platform.internal.NativeLibraryLoader in an unnamed
module (...)
WARNING: Use --enable-native-access=ALL-UNNAMED to avoid a warning for
callers in this module
WARNING: Restricted methods will be blocked in a future release unless
native access is enabled

This breaks run_debug_test_android and run_release_test in the
devicelab.

Gradle fixed this upstream in 8.14 by adding an `Enable-Native-Access:
ALL-UNNAMED` manifest attribute to gradle-wrapper.jar and launching it
from gradlew via `-jar`. However, the Gradle wrapper that flutter_tools
injects into projects (bin/internal/gradle_wrapper.version) was a clone
from Gradle 2.10 in 2017. Its gradlew launches it via `-classpath`, so
it doesn't pick up the fix.

We now invoke gradle with `--enable-native-access=ALL-UNNAMED` via
GRADLE_OPTS. I verified and this flag is supported on JDK 17 (our
Android minimum). This fixes the warning regardless of which wrapper a
project uses. We'll want to update the injected wrapper in a followup
patch.

We copy the wrapper into every new project on `flutter create` and
inject into any project where it's missing on `flutter build` but we
never overwrite the wrapper if it exists, so we'll likely want this
change regardless, or at least until that issue is solved.

See: https://openjdk.org/jeps/472
See: gradle/gradle#31625


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