[Android] Do not set explicit versions in build.gradle

[m-bert]

Description

Gesture Handler loads specific Kotlin version during build. This is unnecessary and may cause build warnings, such as one described in #2307.

This PR removes pinning of specific kotlin/gradle versions when Gesture Handler is not root project, so we fallback to the ones declared by the root. Unfortunately we can't simply remove those lines, as spotless would fail.

Fixes #2307

Test plan

Tested that android build correctly in basic-example, expo-example and standalone app.

[m-bert]

I'm not sure if we want to remove it entirely, or add info that it is not supported anymore (e.g. starting from 3.1.0)

[Copilot]

Pull request overview

This PR reduces Android build warnings about the Kotlin Gradle plugin being loaded multiple times by avoiding adding an explicit kotlin-gradle-plugin classpath dependency when the root project already provides it. It also updates the installation docs to remove guidance about forcing a specific Kotlin version for RNGH.

Changes:

• Conditionally adds org.jetbrains.kotlin:kotlin-gradle-plugin to the buildscript classpath only when the root project does not already include it.
• Removes the documentation section describing how to override RNGH’s Kotlin version via ext.kotlinVersion.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
packages/react-native-gesture-handler/android/build.gradle	Adds a root-project classpath check to avoid explicitly loading the Kotlin Gradle plugin when it’s already provided.
packages/docs-gesture-handler/docs/fundamentals/installation.mdx	Removes Kotlin-version override instructions from the Android installation docs.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.