bpo-41877: Check for misspelled speccing arguments (GH-23737)

patch, patch.object and create_autospec silently ignore misspelled
arguments such as autospect, auto_spec and set_spec. This can lead
to tests failing to check what they are supposed to check.

This change adds a check causing a RuntimeError if the above
functions get any of the above misspellings as arguments. It also
adds a new argument, "unsafe", which can be set to True to disable
this check.

Also add "!r" to format specifiers in added error messages.