text: change default char_whitelist parameter.

[Kumataro]

Fix #3457

This patch changes char_whitelist default from [0-9a-zA-Z] to all characters.

Current setting text module missrecognizes in CJK and other languages in default because it accepts only [0-9a-zA-Z].

And in "eng" language, wordlist contains some characters outside of [0-9a-zA-Z].
Those words are not recognized with default parameters.

So to disable whitelist is better than using "0-9a-zA-Z".

Pull Request Readiness Checklist

See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

• I agree to contribute to the project under Apache 2 License.
• To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
• The PR is proposed to the proper branch
• There is a reference to the original bug report and related work
• There is accuracy test, performance test and test data in opencv_extra repository, if applicable
  Patch to opencv_extra has the same branch name.
• The feature is well documented and sample code can be built with the project CMake

[n0099]

LGTM