Simplified logic to show three part version, removing the revision

[santhoshb-msft]

This pull request includes changes to the AppVersionService implementation across multiple files, simplifying how the application version is handled and removing unnecessary properties. The most important changes include updating the service registration in Startup.cs files, removing redundant properties from the IAppVersionService interface, and modifying the AppVersionService class to use the Version class instead of FileVersionInfo.

Changes to service registration:

• src/AdminSite/Startup.cs: Updated the ConfigureServices method to register IAppVersionService using the Version class instead of FileVersionInfo.
• src/CustomerSite/Startup.cs: Updated the ConfigureServices method similarly to the AdminSite to use the Version class.

Simplification of IAppVersionService:

• src/Services/Contracts/IAppVersionService.cs: Removed unnecessary properties ProductMajorPart, ProductMinorPart, and ProductBuildPart.

Modification of AppVersionService:

• src/Services/Services/AppVersionService.cs: Changed the constructor to accept a Version object and simplified the version string construction. Removed the now redundant properties.

Code cleanup:

• src/Services/Services/AppVersionService.cs: Added missing using System; directive.

[fthorntonai]

Approved 3 part version displays in Apps AdminPortal and Client Portal