types: Separate Args and Signature

[johanrd]

IfElement and Blocks is included in the main component interface, Args needs its own property.

I had the following glint 2345 error when consuming the PowerSelect component, as it expected Element and Blocks to be passed in as required arguments:

NamedArgs<PowerSelectArgs> (…) is missing the following properties from type 'PowerSelectArgs': Element, destination, Blocks glint(2345)

[johanrd]

fixes #1585

[mkszepp]

Thank you!