fix(formatter): improve JSON output formatting

[mrrobot47]

This pull request updates the JSON output formatting in the php/EE/Formatter.php file to improve readability by using pretty-printed JSON. This affects both the main formatting function and the single field display function.

Improvements to JSON output formatting:

• Updated the format function to use JSON_PRETTY_PRINT when outputting JSON, making the output easier to read. If JSON_PARTIAL_OUTPUT_ON_ERROR is available, both flags are used together.
• Updated the show_single_field function to use JSON_PRETTY_PRINT for single field JSON output.