fix: "no such file or directory" error when using Gradle Kotlin DSL

[mateusz1913]

Summary:

According to #1567 (comment), older CLI versions do not handle build.gradle.kts as valid Gradle scripts, during autolinking.

This PR adds an additional check for default path to build.gradle.kts and throws an error, if there is no file at path.

Test Plan:

• Create project with cli v6 and build.gradle rewritten from Groovy DSL to Kotlin DSL (you can use https://github.com/mateusz1913/RNKotlinPOC)
• Add library which requires autolinking on Android
• Run Android app

[thymikee]

Thanks for porting this to 6.x as well 👍🏼