Expose $contentTypeName in UFM expressions

[albintoxic]

Current behaviour

By default the block's content type name is rendered as the block label in a block list. UFM expressions currently expose property values like $index, and $settings. There is no way to access the block's content type name dynamically in the block label template, meaning the only option is to hardcode it in each label template.

Desired behaviour

Expose a reserved variable such as $contentTypeName in the UFM expression context, enabling patterns like:

${ heading.length > 0 ? heading : $contentTypeName }

or as a parameter in UFM components:

{umbValue: heading | fallback: $contentTypeName }

Why

Hardcoding the type name is prone to manual complexity since if a content type is renamed, every block label template referencing it must be updated manually. The $contentTypeName variable was also available in Umbraco 13 block label templates, thus this would restore parity with previous functionality.

Achieving this today requires building a custom UFM component, which is a significant overhead for what should be a simple, common use case that I believe many could benefit from (or perhaps its just me 😄)