Add dependencies between native build tasks and Java header generation

[rorbech]

The native build task has a dependency for each abi, so we need to add a dependency to the Java header generating task for each of the native build tasks.

[rorbech]

Just to shed some light on what this changes means ... this is the dump of the pairs of externalNativeBuildDependency and compile${variant.name.capitalize()}JavaWithJavac for the various variants.

buildCMakeDebug[armeabi-v7a][realm-jni] compileBaseDebugJavaWithJavac
buildCMakeDebug[arm64-v8a][realm-jni] compileBaseDebugJavaWithJavac
buildCMakeDebug[x86_64][realm-jni] compileBaseDebugJavaWithJavac
buildCMakeDebug[x86][realm-jni] compileBaseDebugJavaWithJavac
buildCMakeDebug[armeabi-v7a][realm-jni]-2 compileObjectServerDebugJavaWithJavac
buildCMakeDebug[x86][realm-jni]-2 compileObjectServerDebugJavaWithJavac
buildCMakeDebug[arm64-v8a][realm-jni]-2 compileObjectServerDebugJavaWithJavac
buildCMakeDebug[x86_64][realm-jni]-2 compileObjectServerDebugJavaWithJavac
buildCMakeRelWithDebInfo[x86][realm-jni] compileBaseReleaseJavaWithJavac
buildCMakeRelWithDebInfo[x86_64][realm-jni] compileBaseReleaseJavaWithJavac
buildCMakeRelWithDebInfo[arm64-v8a][realm-jni] compileBaseReleaseJavaWithJavac
buildCMakeRelWithDebInfo[armeabi-v7a][realm-jni] compileBaseReleaseJavaWithJavac
buildCMakeRelWithDebInfo[x86][realm-jni]-2 compileObjectServerReleaseJavaWithJavac
buildCMakeRelWithDebInfo[x86_64][realm-jni]-2 compileObjectServerReleaseJavaWithJavac
buildCMakeRelWithDebInfo[arm64-v8a][realm-jni]-2 compileObjectServerReleaseJavaWithJavac
buildCMakeRelWithDebInfo[armeabi-v7a][realm-jni]-2 compileObjectServerReleaseJavaWithJavac

[cmelchior]

Nice find. If CI is happy 🚀