fix: Minify JSON objects/arrays in Spark get_json_object

[wecharyu]

1. Remove whitespace after ',' to align result with spark
2. Fix some edge cases of path $:
   a. Supports trailing spaces in $ path, eg: '$ '
   b. Fix the result of redundant json input, eg: '["a", "b"], {}' -> "["a","b"]"
   c. Fix the result of scalar json input, eg: '2e-3' -> 0.002

fix: #14800

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[rui-mo]

@PHILO-HE Would you like to review this change? Thanks.