json Component - Add the input string to the parse_json function in the error message

**Describe the problem you have/What new integration you would like**

I'd like to see the input string to the `parse_json` function to aid debugging.

https://github.com/esphome/esphome/blob/fea05e9d33f13a5435f035bcf10d0ea0ef23abc8/esphome/components/json/json_util.cpp#L94

**Please describe your use case for this integration and alternatives you've tried:**

Being able to check what was passed to the json_util function would have aided in tracking down an issue.

**Additional context**

Start with esphome/components/json/json_util.cpp at the linked parse_json implementation around line 94. Trace how parse errors are reported and determine where the input string belongs in that message. Done means the parse_json error includes the supplied input string and the JSON component checks still pass.

Written by the indexing model from the issue text.