[Bug] The suggested partitioning scheme breaks silent authentication

[chlowell]

...because clients suggest partition keys inconsistently. For example, here's a repro using interactive auth:

package main

import (
	"context"
	"fmt"
	"path"
	"runtime"

	"github.com/AzureAD/microsoft-authentication-library-for-go/apps/cache"
	"github.com/AzureAD/microsoft-authentication-library-for-go/apps/public"
)

type logger struct{}

func (*logger) Replace(ctx context.Context, cache cache.Unmarshaler, cacheHints cache.ReplaceHints) error {
	pc, _, _, _ := runtime.Caller(2)
	details := runtime.FuncForPC(pc)
	fmt.Printf("%s called Replace with suggested partition key %q\n", path.Base(details.Name()), cacheHints.PartitionKey)
	return nil
}

func (*logger) Export(ctx context.Context, cache cache.Marshaler, cacheHints cache.ExportHints) error {
	pc, _, _, _ := runtime.Caller(2)
	details := runtime.FuncForPC(pc)
	fmt.Printf("%s called Export with suggested partition key %q\n", path.Base(details.Name()), cacheHints.PartitionKey)
	return nil
}

func main() {
	pca, err := public.New("04b07795-8ddb-461a-bbee-02f9e1bf7b46", public.WithCache(&logger{}))
	if err != nil {
		panic(err)
	}
	ctx := context.Background()
	scopes := []string{"https://management.azure.com//.default"}
	ar, err := pca.AcquireTokenInteractive(ctx, scopes)
	if err != nil {
		panic(err)
	}
	_, err = pca.AcquireTokenSilent(ctx, scopes, public.WithSilentAccount(ar.Account))
	if err != nil {
		panic(err)
	}
}

Output:

public.Client.AcquireTokenInteractive called Replace with suggested partition key ""
public.Client.AcquireTokenInteractive called Export with suggested partition key ""
base.Client.AcquireTokenSilent called Replace with suggested partition key "oid.tid"

Only AcquireTokenSilent suggests a key. It therefore always fails for an application using the key to look up a partition because the partition in question will always be empty or nonexistent, because AcquireTokenInteractive didn't suggest that key after acquiring tokens.

Part, if not all, of the problem is that AuthParams.CacheKey() doesn't consider all values of AuthorizationType (the value is ATInteractive in interactive auth). Maybe it should have a default case? I see there's also TokenResponse.CacheKey(). That may also need an update, or perhaps there's a way to consolidate these methods.

Another part of the problem is test gaps--neither CacheKey() is tested, nor is the value of AuthParams.AuthorizationType set by AcquireToken methods.