Add setting to group outer walls

[casperlamboo]

Description

This pr add a setting to the front end to group walls.

Frontend-PR: https://github.com/Ultimaker/Cura/pull/16813

Type of change

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Printer definition file(s)
• [ ] Translations

How Has This Been Tested?

Ran from source

Test Configuration: MacOS

Checklist:

• [x] My code follows the style guidelines of this project as described in UltiMaker Meta and Cura QML best practices
• [x] I have read the Contribution guide
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I have uploaded any files required to test this change

CURA-11082

[github-actions[bot]]

Unit Test Results

26 tests  ±0   26 :heavy_check_mark: ±0   16s :stopwatch: -1s   1 suites ±0     0 :zzz: ±0    1 files   ±0     0 :x: ±0 

Results for commit ec8bcfc3. ± Comparison against base commit 309adf8c.