Replace PlanModel using the __doc__ of a plan with using Annotated pydantic fields

[DiamondJoseph]

blueapi controller plans returns a description of the plans that are available in the context. Currently this comes from the docstring of the plan function. This should get also/instead(?) the description of the Pydantic model that is constructed, including information about the fields of the plan: defaults, types, limits etc.

Using Annotated allows us to have this information presented as part of the json schema, and reduce the amount of information required in the docstring.

[DiamondJoseph]

e.g.

def stp_snapshot(
    detectors: list[Readable],
    temperature: Movable = inject("sample_temperature"),
    pressure: Movable = inject("sample_pressure"),
) -> MsgGenerator:
    """
    Moves devices for pressure and temperature (defaults fetched from the context)
    and captures a single frame from a collection of devices

    Args:
        detectors (List[Readable]): A list of devices to read while the sample is at STP
        temperature (Optional[Movable]): A device controlling temperature of the sample,
            defaults to fetching a device name "sample_temperature" from the context
        pressure (Optional[Movable]): A device controlling pressure on the sample,
            defaults to fetching a device name "sample_pressure" from the context
    Returns:
        MsgGenerator: Plan
    Yields:
        Iterator[MsgGenerator]: Bluesky messages
    """

then becomes

def stp_snapshot(
    detectors: set[Readable] = Annotated[
        Field(set[Readable], min_length=1), "Devices to read while the sample is at STP"
    ],
    temperature: Movable = Annotated[
        inject("sample_temperature"), "A device controlling temperature of the sample"
    ],
    pressure: Movable = Annotated[
        inject("sample_pressue"), "A device controlling pressure of the sample"
    ],
) -> MsgGenerator:
    """
    Moves devices for pressure and temperature (defaults fetched from the context)
    and captures a single frame from a collection of devices
    """

And the information about the detector minimum length (bad example) gets propagated through.