fix(AIENG-359): Improve text detection by using ByteBuffer and charse…

[psakthivel04]

This pull request updates the logic for detecting whether a file is text or binary in the GitFile class and adds comprehensive tests to ensure correctness. The main change replaces the previous character-based reading approach with a more robust UTF-8 decoder, and new unit tests are introduced to cover various scenarios.

Improvements to text/binary file detection:

• The isText() method in GitFile now uses a UTF-8 decoder with strict error reporting to determine if file content is valid UTF-8, making detection of binary files more accurate and efficient.

Testing enhancements:

• Added a new test class GitFileTest with unit tests for isText(), covering text files, binary files, and multi-byte UTF-8 content.
• Registered GitFileTest in the AllTests suite to ensure it is run with other tests.

Code cleanup:

• Removed unused imports and added necessary ones in GitFile.java to support the new decoding logic.

[Konboi]

This change sounds nice however we need to fix this change not only the smart-tests-cli command (v2) but also the launchable command (v1), right?
So, could you create a PR from v1 branch and merge into v1, fist? Next, please merge v1 branch into the main.

Also when you update the Java code, please run build-java.sh to update exe_deploy.jar file