CanonRFLensType values are wrong in canonmn_int.cpp

[EC1000]

Describe the bug

canonRFLensType values are wrong in https://github.com/Exiv2/exiv2/blob/main/src/canonmn_int.cpp#L2462-L2482 (257 for all Canon RF lenses, while it should be a different number for each lens except Canon RF 50mm F1.2L USM).

Expected behavior

The correct values are described here: https://exiftool.org/TagNames/Canon.html (search "RFLensType").

[postscript-dev]

@EC1000: Unlike ExifTool, Exiv2 usually adds a test image to demonstrate each of the different lenses containing that description. The Exif.CanonFi.RFLensType values in your post were added in #1451, but for some reason didn't include test images. @alexvanderberkel where did the lens information come from?

[alexvanderberkel]

@postscript-dev I did notice the issue as well and started to work on correcting the issue ##1628. However, I didn't find the time to complete the pull request with test images etc. so far.

[postscript-dev]

@alexvanderberkel: No problem. As you have experience with Canon cameras, are you free to deal with this current issue?

[alexvanderberkel]

I would like to finish that pull request. It should fix the issue in version 1.0, though I'm still a bit limited timewise...