Added support for operationId and handlers path

[sgermain06]

Added a way to allow handlers to call specific methods, defined by operatrionId. Also added a unified way to define a base path for handlers, allowing the x-hapi-handler record to simply call the path to a file without needing to change directories back to the previous one or forcing the handler files to be in the same directory as the OpenAPI definition file.

const init = async () => {
    await server.register({
        plugin: require('hapi-openapi'),
        options: {
            api: './api/swagger/swagger.yaml',
            handlersPath: './api/controllers', // <-- This is where the plugin should look to resolve controllers defined in x-hapi-handler
        }
    });
    await server.start();
    console.log(server.info.uri);
};

{
    ...
    "paths": {
        "/firstPet": {
            "x-hapi-handler": "pets",
            "get": {
                "description": "Returns all pets from the system that the user has access to",
                "operationId": "getFirstPet",
                "produces": [
                    "application/json",
                    "application/xml",
                    "text/xml",
                    "text/html"
                ],
                "responses": {
                    "200": {
                        "description": "pet response",
                        "schema": {
                            "$ref": "#/definitions/pet"
                        }
                    },
                    "default": {
                        "description": "unexpected error",
                        "schema": {
                            "$ref": "#/definitions/errorModel"
                        }
                    }
                }
            }
        },
        ...
    }
}

This should call the getFirstPet function in the file that's located in <__dirname>/api/controllers/pets.js

[dcharbonnier]

pathsearchMethod => pathSearchMethod
maybe pathSearchWithMethod

[dcharbonnier]

the handler in case of x-hapi-handler is already set few lines before, this is probably a bug as we probably wanted precedence of x-hapi-handler over a path but now we do it twice.

[dcharbonnier]

I guess we are searching for `xxx/Undefined; most of the time and do a disk access