Simplify creating content from a blueprint programmatically

[lauraneto]

Relates to #19352, but for V16.

This pull request includes the following changes:

• Adjust the ContentBlueprintEditingService.GetScaffoldedAsync() to return a copy of the blueprint, instead of the blueprint itself, with the identity reset. This will allow developers to simply call this method and save the content as a new item without much effort.
• Rename ContentService.CreateContentFromBlueprint() to ContentService.CreateBlueprintFromContent(), as this better explains its purpose (and how it is used in the core). Marked the old method as obsolete, with a message and xml docs mentioning the other methods.
• Created an integration test to make sure that when creating content from a blueprint, using the different block editors, the keys are replaced with new ones.
  • Moved some of the code for creating simple block data types from ElementSwitchValidatorTests to DataTypeBuilder, so it could be re-used.

[Copilot]

Pull Request Overview

This PR simplifies programmatic blueprint-based content creation by returning clone scaffolds, renaming key methods for clarity, and expanding integration tests for block editors.

• GetScaffoldedAsync now returns a cloned blueprint with reset identity.
• Renamed CreateContentFromBlueprint → CreateBlueprintFromContent, marking the old method obsolete.
• Added integration tests covering block editors and extracted reusable block data type builder logic.

Reviewed Changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
tests/Umbraco.Tests.Integration/Umbraco.Infrastructure/Services/ContentBlueprintEditingServiceTests.cs	Added JSON serializer dependency and adjusted array initializers.
tests/Umbraco.Tests.Integration/Umbraco.Infrastructure/Services/ContentBlueprintEditingServiceTests.GetScaffold.cs	Enhanced scaffold tests for block editors; introduced new block key assertions.
tests/Umbraco.Tests.Integration/Umbraco.Core/Services/TelemetryProviderTests.cs	Updated a test to use GetScaffoldedAsync and switched to async.
tests/Umbraco.Tests.Integration/Umbraco.Core/Services/ElementSwitchValidatorTests.cs	Refactored data type setup to use new CreateSimpleElementDataType.
tests/Umbraco.Tests.Integration/Umbraco.Core/Services/ContentServiceTests.cs	Renamed test and updated calls to use CreateBlueprintFromContent.
tests/Umbraco.Tests.Integration/Testing/UmbracoIntegrationTestWithContent.cs	Added IDataTypeService to test base class.
tests/Umbraco.Tests.Common/Builders/DataTypeBuilder.cs	Introduced CreateSimpleElementDataType helper and moved block configuration logic.
src/Umbraco.Core/Services/IContentService.cs	Renamed interface methods, added default implementation, marked old method obsolete.
src/Umbraco.Core/Services/ContentService.cs	Renamed and refactored content/blueprint creation methods, updated null checks.
src/Umbraco.Core/Services/ContentBlueprintEditingService.cs	Implemented deep-clone scaffold logic and updated notification payload.

Comments suppressed due to low confidence (2)

tests/Umbraco.Tests.Integration/Umbraco.Infrastructure/Services/ContentBlueprintEditingServiceTests.GetScaffold.cs:88

• Initializing a List with [] causes a type mismatch. Replace with new List<Guid>() or use a collection expression that returns List.

List<Guid> newKeys = [];

tests/Umbraco.Tests.Common/Builders/DataTypeBuilder.cs:172

• Default switch arm returns [] which is an empty array, not a Dictionary<string, object>. Use new Dictionary<string, object>() instead.

_ => [],

[AndyButland]

This looks fantastic, excellent work on the integration tests. I could only find one nit-pick that I've suggested, other than that all good to merge in and close off the related issue.