Enable more retraction settings to be set per-model

[jeremysalwen]

Description

This allows more retraction settings to be set per-object. These retraction settings were already supported on a per-object basis on the backend by Ultimaker/CuraEngine#1769, but were not enabled by the corresponding frontend PR at the time.

This helps get incrementally closer to exposing per-model settings #3193

Type of change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

Tested the g-code output after changing per-object settings. (e.g. add two objects, set retraction distance do something different on one of them, check that this modifies the output g-code by diffing the g code before and after the change.)

Test Configuration:

• Operating System: Debian

Checklist:

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

[github-actions]

Test Results

23 703 tests  +23 703   23 701 ✅ +23 701   46s ⏱️ +46s
     1 suites +     1        2 💤 +     2 
     1 files   +     1        0 ❌ ±     0 

Results for commit cf52772. ± Comparison against base commit 2bfb2fd.