fix(android): register compat Kotlin source dirs for AGP 8.9+ (RN 0.86)

[joaquinvaz]

Description

Fixes #4263

On the React Native 0.86 Android toolchain, appending a directory to java.srcDirs in android/build.gradle no longer registers it as a Kotlin source root for the compileKotlin task. The compat directories added there — mapbox-v11-compat/v11, rn-compat/rn75, and the selected lifecycle-compat/* variant — contain only Kotlin sources, so they are silently skipped and their packages (e.g. com.rnmapbox.rnmbx.v11compat) fail to resolve, breaking the Android build.

Fix: after all the conditional java.srcDirs += additions, mirror them onto the Kotlin source set:

// Guarded by the same RNMapboxMapsImpl == "mapbox" check as the kotlin-android
// plugin, since only that impl registers the `kotlin` source set.
if (safeExtGet("RNMapboxMapsImpl", defaultMapboxMapsImpl) == "mapbox") {
    kotlin.srcDirs(java.srcDirs)
}

One placement covers every current and future compat dir.

⚠️ Speculative fix — reproduction caveat (per .github/REPRODUCING.md)

I want to be upfront rather than overclaim:

• I could not reproduce this in /example as-is: it's pinned to RN 0.84.1 (Gradle 9.0.0 / AGP 8.9+) and builds fine there — including in android-actions.yml CI. So this is not a plain "AGP 8.9+" bug; the trigger is the RN 0.86 toolchain specifically (its AGP + Kotlin Gradle Plugin combination). Reproducing in /example would require bumping it to RN 0.86.
• The bug does reproduce in a downstream app on RN 0.86 / Gradle 8.14.3, where the equivalent change (applied as a yarn patch to android/build.gradle) is what made the Android build succeed. Without it: unresolved references to the v11compat / rncompat packages. With it: clean compile.