add support for HTTPMethodView

[morentharia]

from sanic.views import HTTPMethodView
from sanic.response import json

class CarHandler(HTTPMethodView):
    @doc.summary("Get a car")
    async def get(self, request):
        return json(dict(get='get'))

    @doc.summary("Post a car")
    async def post(self, request):
        return json(dict(post='post'))

[wswld]

This would indeed be very useful.

[sebjamesfd]

@morentharia Nice work!

Unfortunately this will not add the blueprint tags to each method resulting in swagger showing the methods as belonging to the "default" blueprint.

Some similar work of retrieving the route_specs of each method and then assigning the blueprint name as tags to each here https://github.com/channelcat/sanic-openapi/blob/master/sanic_openapi/openapi.py#L50

[ahopkins]

How is this different than #64? Do we need this still? Can we get rid of one of them?

[logileifs]

Can we get this pull request or 64 merged?
Is there something I can do to help? I could resolve the conflicts if that's the only thing keeping this from being merged

[chenjr0719]

Thanks for contribution but I'm going to close this PR because it is duplicated with #64.