[Transformers] Add an argument trust_remote_code on transformers pipeline initialization.

[dbogunowicz]

Give a user an option to enable running remote code through pipeline argument e.g.

Pipeline.create(task="...", trust_remote_code = True)

By default trust_remote_code=False.

[mgoin]

Thank you!
Side note: I think there is a problem with discoverability for arguments that are inherited by pipeline. Maybe this would be "solved" by autogenerated docs but I'm not sure how to make it more visible just looking at the constructors

[rahul-tuli]

LGTM! could you update the PR description with an example of what does this option allow a user to do that wasn't possible before?