Name the forbidden character in the port name error

[dv-picknik]

Fixes #1221.

CreatePort now names the character when a port name contains one of the characters rejected since 4.8.4, using the same wording as the XML path:

Port name 'goal.pose' contains forbidden character '.'

Other invalid names, such as name, ID or a leading _ or digit, still get the existing message.

To share the wording, formatForbiddenChar moves from the anonymous namespace in xml_parsing.cpp to basic_types.h/.cpp, next to findForbiddenChar. CreatePort is defined in the header and needs it. This adds one public function and changes no existing signature.

NameValidation.CreatePort_NamesForbiddenChar covers a printable character and a control character. It fails on master and passes with this change. The full suite passes, and so does pre-commit.

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