Convert dependency type from struct to tuple

[ishkawa]

Currently, dikitgen expects that Injectable.Dependency is declared as a struct.

Structs can have computed properties and methods, but the type elements are not related to declaring dependencies. I think Injectable.Dependencyshould focus on expressing dependencies, and the other works should be done by other components.

To encourage developers to focus on defining dependencies, I'm planning to convert Injectable.Dependency to tuple type.

[takasek]

Single dependency cannot be tuple type. Do you have any plan to represent it?