…Metadata section of minigraph file (#7031)

Parse the value `AutoNegotiation` element from the `LinkMetadata` section of minigraph file. If the element is present, an `autoneg` key will be added to the port in the `PORT` table of Config DB with a value of either `off` or `on`

If an `autoneg` value is present in port_config.ini, the value from the minigraph will take precedence, overriding that value.

Also remove `AutoNegotiation` and `EnableAutoNegotiation` elements from the `DeviceInfo` section, as we will use this data in the `LinkMetadata` section to determine whether to enable auto-negotiation for a port.