fix IOException in BuildCodegenCLITask (#48008)

Summary:
building RN tester with 0.77 rc-0 doesn't work now because of `java.io.IOException:  No such file or directory` on line 48.

`buildDirectory` is a Gradle property representing a file

https://github.com/facebook/react-native/pull/47552 removes this file altogether so feel free to close if that one is the "right one"

## Changelog:

[ANDROID] [FIXED] - fix IOException in `BuildCodegenCLITask`

Pull Request resolved: https://github.com/facebook/react-native/pull/48008

Test Plan: After this change, building RN tester works.

Reviewed By: cortinico

Differential Revision: D66650038

Pulled By: robhogan

fbshipit-source-id: 11cd83493fa118c6b79d11c9113228dd3971a803

packages/gradle-plugin/react-native-gradle-plugin/src/main/kotlin/com/facebook/react/tasks/internal/BuildCodegenCLITask.kt

@@ -39,7 +39,7 @@ abstract class BuildCodegenCLITask : Exec() {
       }
 
   override fun exec() {
-    val logfile = "${project.layout.buildDirectory}/build-cli.log"
+    val logfile = "${project.layout.buildDirectory.getAsFile().get()}/build-cli.log"
     File(logfile).apply {
       parentFile.mkdirs()
       if (exists()) {