PRI-59: Fix improper input validation in safeJsonParse

[jintukumardas]

Linear: https://linear.app/shm/issue/PRI-59
Summary: Added input type validation for base64 and unit tests

[github-actions]

PR Reviewer Guide 🔍

⏱️ Estimated effort to review: 2 🔵🔵⚪⚪⚪

🧪 PR contains tests

🔒 No security concerns identified

⚡ Key issues to review Type Checking The type checking for originalObject.value only checks for string type but does not validate if the string is a valid base64 format. This might still allow invalid base64 strings to pass through until they are processed, potentially leading to errors at runtime.

The merge-base changed after approval.