[CIS Azure] Asset inventory / fetchers

[jeniawhite]

Motivation
In order to fetch the resources we have multiple solution paths:

• Write fetchers for every resource type
• Utilize Azure resource graph capabilities

The focus is to have something similar to asset inventory and avoid writing fetchers.
This is why I've focused on the ARG and implemented a small POC in order to see if it is a viable option.

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package main

import (
	"context"
	"fmt"
	"log"

	"github.com/Azure/azure-sdk-for-go/sdk/azcore/to"
	"github.com/Azure/azure-sdk-for-go/sdk/azidentity"
	"github.com/Azure/azure-sdk-for-go/sdk/resourcemanager/resourcegraph/armresourcegraph"
)

func main() {
	cred, err := azidentity.NewDefaultAzureCredential(nil)
	if err != nil {
		log.Fatalf("failed to obtain a credential: %v", err)
	}
	ctx := context.Background()
	clientFactory, err := armresourcegraph.NewClientFactory(cred, nil)
	if err != nil {
		log.Fatalf("failed to create client: %v", err)
	}
	res, err := clientFactory.NewClient().Resources(ctx, armresourcegraph.QueryRequest{
		// Query: to.Ptr("Resources | where type =~ 'Microsoft.Storage/StorageAccounts' | limit 1"),
		Query: to.Ptr("Resources"),
		Subscriptions: []*string{
			to.Ptr("SUB_ID")},
	}, nil)
	if err != nil {
		log.Fatalf("failed to finish the request: %v", err)
	}
	fmt.Printf("%v", res.Data)
}

Running this on my subscription resulted in a response with all of the resources inside the subscription.
There is also an option to run the queries on management groups.

Definition of done
What needs to be completed at the end of this task

• Implement fetching of resources using ARG with pagination
• Support management groups