add octoprint and prusa support + refactor Printer Type

[d3vyce]

I refactor Printer class to allow multiple 3D printer vendor.

To add a new printer type class have to be a child class of Printer. It is then possible to add different variables depending on the type of printer: for example, a token for the use of an API. The class must contain 3 functions:

• connect: connect to printer (if necessary)
• send: send file to printer
• disconnect: disconnect from printer (if necessary)

Here's a snipset of a typical class:

class XXXXX(Printer):
    def __init__(self, config: dict) -> None:
        Printer.__init__(self, config)

        self.xxx = config.get("xxx")
        self.yyy= config.get("yyy")

    def connect(self) -> None:
        # code to connect
        self.connected = True

    def send(self, filename: str, file: io.BytesIO, logger: queue.Queue) -> bool:
        for _ in range(1, MAX_SEND_RETRY+1):
                # code to send file
                return True
        return False

    def disconnect(self) -> None:
        # code to disconnect
        self.connected = False

I've also added (and tested) integration with octoprint and prusa (mini, mk4, xl).