4.x: Two simple fixes to We Chat QR Code module

[elatkin]

Two simple fixes to We Char QR Code module:
- decodemgr.cpp: fix messed: width <--> height
- unicomblock.cpp: fix wrong type at sizeof(...)

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

allow_multiple_commits=1

[elatkin]

Dear reviewers!

CI failes at opencv_perf_wechat_qrcode test at 2_qrcodes.png image,
like this log (as I can reproduce this failure at my local machine):

• 20240318_pr3698_x86_fail_2_qrcodes.log

However, I think this regression is not caused by this pull-request. 🤔
Algorithm appears too sensitive; this test case may pass or fail by occasion,
as such test image may be too difficult for decoding with this algorithm.

What if we fix/update this test: try another picture with 2 QR codes, easier
for decoding, which my fixed variant of algorithm would be able to process?
Specifically, I propose simpler picture with my pull-request to opencv_extra:

• PR #1156 fix opencv_perf_wechat_qrcode failure by simplifying test image

[mshabunin]

This image is excluded from accuracy test:

opencv_contrib/modules/wechat_qrcode/test/test_qrcode.cpp

Lines 44 to 46 in bf95e79

	std::string qrcode_images_multiple[] = {/*"2_qrcodes.png",*/ "3_close_qrcodes.png", /*"3_qrcodes.png",
	"4_qrcodes.png", "5_qrcodes.png", "6_qrcodes.png",*/
	"7_qrcodes.png"/*, "8_close_qrcodes.png"*/};

I suggest excluding it from perf test too.

[elatkin]

@mshabunin
Could you please review once again? I have added new commit to exclude 2_qrcodes.png, like you propose.

[mshabunin]

Looks good to me!