create_opfshould provide which type of OpenPecha object should be created

[10zinten]

since, we have separated git logic from OpenPechaFS into OpenPechaGitRepo with #224 the create_opf should be flexible enough to return any type of OpenPecha variant.

Suggestions

1. Class dependency injection

---

Cons:

• no code completion with modern code editor

def create_opf(self, ..., pecha_class: OpenPecha):
    pecha = pecha_class(metadata=metadata)
    ...
    return pecha

2. Object dependency injection

---

Cons:

• no code completion with modern code editor

def create_opf(self, ..., pecha: OpenPecha):
    ...
    return pecha

[eroux]

I like the object dependency injection better