feat(Common/SCM): Add foundational DTOs for SCM operations

This commit introduces four new Data Transfer Objects (DTOs) in the `Common` crate's Source Control Management module:
- `SourceControlCreateDTO`
- `SourceControlUpdateDTO`
- `SourceControlGroupUpdateDTO`
- `SourceControlInputBoxDTO`

These DTOs define the core data structures required for SCM operations in Land's final architecture. As part of the abstract `Common` layer, they:
1. Establish standardized contracts for SCM resource manipulation that will be implemented by `Mountain`'s native Git handlers
2. Enable type-safe communication over the `Vine` gRPC layer between `Mountain` and `Cocoon`
3. Support Workflow #8 (SCM) by modeling operations like resource creation/updates and input box interactions
4. Provide the foundation for `Wind` UI components to render SCM views using consistent data structures

The additions complete the initial SCM DTO suite and align with recent abstractions added for Keybinding and ExtensionManagement services.

Author: NikolaRHristov

Source/SourceControlManagement/DTO/mod.rs

@@ -5,6 +5,10 @@
 
 #![allow(non_snake_case, non_camel_case_types)]
 
+pub mod SourceControlCreateDTO;
+pub mod SourceControlUpdateDTO;
+pub mod SourceControlGroupUpdateDTO;
+pub mod SourceControlInputBoxDTO;
 pub mod SourceControlManagementGroupDTO;
 pub mod SourceControlManagementProviderDTO;
 pub mod SourceControlManagementResourceDTO;