Update r2 and fix renamed configuration variables.

[karliss]

Your checklist for this pull request

• I've read the guidelines for contributing to this repository
• I made sure to follow the project's coding style
• I've updated the documentation with the relevant information (if needed)

Detailed description

Update r2 to 4.5. Don't merge before 4.5 is tagged!

Test plan (required)

• Open Cutter 1.10.3, change the values for asm.var.subonly and asm.bytespace. ✔️
• Check that they are saved in cutter.in ✔️
• Open with the new Cutter ✔️
• Make sure names in cutter.in have been correctly updated preserving old value ✔️
• Make sure log doesn't contain warnings about trying to access non-existing r2 config variables ✔️
• Toggle the settings and restart cutter ✔️
• Make sure the new values are correctly loaded and shown in the settings dialog ✔️
• Close cutter and delete Cutter.ini ✔️
• Start and exit cutter 1.10.3, make sure cutter.ini doesn't contain the renamed variables with either old or new name ✔️
• Open the new cutter and close ✔️
• Make sure setting version has been updated but the variables haven't been added to cutter.ini the same way it was before setting upgrade ✔️

Closing issues

Closes #2278

[XVilka]

The Meson issue looks like mesonbuild/meson#6442

[ITAYC0HEN]

Tested by the test-plan and it looks good :)