Take attribute and property type from type hint

Created by: stanislaw55

Hi, I wanted to share an idea. Right now, when addint attribute (or property) in device class, one need to specify it in constructor like this:

attr = attribute(
        dtype="DevState",
        label="Heat Absorber",
        access=AttrWriteType.READ,
        doc="State of the Heat Absorber",
)

when adding type hint support (for mypy, in example), one has to duplicate the type definition like this

attr: DevState = attribute(
        dtype="DevState",
        label="Heat Absorber",
        access=AttrWriteType.READ,
        doc="State of the Heat Absorber",
)

It would be cool to just define attribute like this

attr: DevState = attribute(
        label="Heat Absorber",
        access=AttrWriteType.READ,
        doc="State of the Heat Absorber",
)

So type is taken from Python's type hint. It would be super nice if it would work with spectrum and image attributes

attr: List[float] = attribute(
        label="Bar",
        access=AttrWriteType.READ,
        doc="Bar attribute",
)
attr: List[List[bool]] = attribute(
        label="Foo",
        access=AttrWriteType.READ,
        doc="Foo attribute",
)

and even max_dim_x and max_dim_y when using Tuple