Add nozzle flow variant & make some options multi-variant (#13712)

# Description

Port BBS per-extruder config variants toggle, thanks Bambu!

Also fix invalid num error when resetting multi-variant filament
overrides.

TODOs:

- [x] Make more configs multi-variant (such as speeds)
- [x] Add flow variant (normal/high flow) combo box
- [x] Add botton to sync config to other variant


# Screenshots/Recordings/Graphs

<img width="846" height="1494" alt="image"
src="https://github.com/user-attachments/assets/47abf053-f5b8-4c86-ac0b-c0323ed8b242"
/>

<img width="1478" height="1189" alt="707420e5be01c30af3e6ede1f3dc9b67"
src="https://github.com/user-attachments/assets/11268712-da65-42ab-9cb8-3cede7790a5c"
/>

<img width="1478" height="1189" alt="81d5d3877f4d5bf9dccd44d7f0b30aa7"
src="https://github.com/user-attachments/assets/cda5ea51-07c3-48fc-bfbb-1428dca14e26"
/>


## Tests

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Fix #10336

src/slic3r/GUI/ConfigManipulation.hpp

@@ -70,7 +70,7 @@ public:
 
     // FFF print
     void    update_print_fff_config(DynamicPrintConfig* config, const bool is_global_config = false, const bool is_plate_config = false);
-    void    toggle_print_fff_options(DynamicPrintConfig* config, const bool is_global_config = false);
+    void    toggle_print_fff_options(DynamicPrintConfig* config, int variant_index, const bool is_global_config = false);
     void    apply_null_fff_config(DynamicPrintConfig *config, std::vector<std::string> const &keys, std::map<ObjectBase*, ModelConfig*> const & configs);
 
     //BBS: FFF filament nozzle temperature range