Added filter to modify entire output of JSON+LD function

Added 'wpseo_json_ld_search_output' filter to allow changes to the entire output of the 'internal_search_json_ld' function. This allows user to add code before or after the output, or modify the existing output.

The JSON+LD code currently breaks any site that optimises Javascript with the Autopimize plugin. This new filter allows user to add 'no optimise' tags around the JSON+LD code.