Renamed ProvidesDescriptorAttribute to DescriptorProviderAttribute

[mdwigley]

Description

Renamed ProvidesDescriptorAttribute to DescriptorProviderAttribute in PlugHub.Shared/Attributes.
This includes:

• Updating the file name to DescriptorProviderAttribute.cs
• Replacing all references across the solution
• Adjusting related tests and documentation

Related Issue

• Resolves Rename ProvidesDescriptorAttribute to DescriptorProviderAttribute #62

Motivation and Context

The new naming improves clarity and aligns with common .NET attribute naming conventions (noun-based + Attribute suffix).
This reduces confusion and makes the attribute’s purpose clearer to contributors.

How Has This Been Tested?

• Built the solution successfully after renaming
• Verified all unit tests pass
• Performed a solution-wide search to confirm old references have been updated

Screenshots (if appropriate):

N/A

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Asset change (adds or updates icons, templates, or other assets)
• Documentation change (adds or updates documentation)
• Plugin change (adds or updates a plugin)

Checklist:

• I have read the CONTRIBUTING document.
• My change requires a change to the core logic.
  • I have linked the project issue above.
• My change requires a change to the assets.
  • I have linked the asset issue above.
• My change requires a change to the documentation.
  • I have linked the documentation issue above.
• My change requires a change to a plugin.
  • I have linked the plugin issue above.