gradle: Validate distribution using SHA256 checksum

[theimpulson]

Summary

Validate Gradle distributions using SHA256 checksums before downloading and using them. This checksum has been obtained from official Gradle docs here

Reference Links

• https://gitlab.com/fdroid/rfp/-/issues/2742
• https://blog.gradle.org/project-integrity
• https://commonsware.com/blog/2023/01/25/gradle-wrapper-supply-chain-attack.html
• https://commonsware.com/blog/2021/01/27/checking-poisoned-projects.html