chore(templates): add type detection on getGlobal utility

[pierrecabriere]

What?

Added proper type detection to the global data fetching utilities in the form builder example. Enhanced the getGlobal and getCachedGlobal functions to leverage TypeScript generics for improved type safety.

Why?

This change improves developer experience by providing proper TypeScript type inference when working with global data. With these changes:
The returned data from getGlobal is now properly typed as DataFromGlobalSlug based on the slug parameter
TypeScript can now correctly infer the return type of getCachedGlobal based on the global slug
This prevents type errors and provides better IDE autocomplete/IntelliSense when accessing properties on retrieved global data

How?

Added import for the DataFromGlobalSlug type from Payload
Made getGlobal a generic function that accepts a type parameter T extends Global
Added proper return type annotation (Promise<DataFromGlobalSlug>) to the getGlobal function
Updated getCachedGlobal to use the same generic typing pattern
These changes maintain the same runtime behavior while enhancing type safety

[paulpopus]

Thank you for working through this, definitely an improved change.

In the instances where these functions are then used, could you please remove the type assignment? Eg for the header

Changing

const headerData: Header = await getCachedGlobal('header', 1)()

To

const headerData = await getCachedGlobal('header', 1)()

And removing the imports please?

[paulpopus]

Thank you so much!