Update index creation in OGM

[katarinasupe]

In GQLA 1.8.0 new index types have been added - #351

With OGM, label and label-property indexes can be created in the following way:

class User(Node):
    id: str = Field(index=True, db=db)
    username: str

class Language(Node, index=True, db=db):
    name: str

This should be aligned with the new indexes added:

• Add the ability to create label-property composite indexes
• Add the ability to create edge-type indexes
• Add the ability to create edge-type property indexes
• Add the ability to create global edge index
• Add the ability to create point index on label and property

The label and label-property behavior currently can be seen as a default behavior, so there is no breaking change. On the other hand, if there is a better way to implement this, consider doing a breaking change.