This adds a restricted version / a wrapper of pandas read_json function. It prohibits reading json from an URL, a file path or a file: only json encoded as str are allowed.

Is this safe to be added to the Wendelin main branch? The original not-restricted function has been blacklisted with this commit: erp5@a254bf50

I added a new unit test for the function.

@tatuya @Tyagov @klaus