Major and breaking changes for SolidDNA v4

[brinkdinges]

Here's my plan:

• Enable mocking: Make SolidDNA objects mockable #38
• Add a few basic tests to prove mocking works
• Update C# version: Update C# version #68 . Is not breaking, but can be confusing and requires Visual Studio 2022.
• File-scoped namespaces
• Add solidworks DLLs to NuGet package: Add solidworks DLLs to NuGet package #72
• Add Source Link
• Add comments to every public type and member
• Refresh coding styles
• Create a CommandManager instance per add-in: Duplicate toolbars and buttons appearing in the incorrect toolbar #67
• Fix lingering Tools menus: Tools menu stays lingering if two add-ins were active and one is unloaded #45
• Optional: adding the oldest supported solidworks version: What should be the oldest solidworks version we support? #18

[brinkdinges]

Adding mocking support by adding interfaces behind all major objects seems to not have caused any breaking changes :)

[brinkdinges]

I had an issue where a Task Pane would leave a grayed-out tab when an add-in unloaded. This is not caused by us, it's fixed in SW2026 🙂