plugin: Update tfsdk.NewProtocol6Server usage with new functions

Reference: hashicorp/terraform-plugin-framework#294

Author: bflad

content/plugin/framework/acctests.mdx

@@ -28,18 +28,15 @@ to supply a map of functions that return a
 To get a `tfprotov6.ProviderServer` from a
 [`tfsdk.Provider`](https://pkg.go.dev/github.com/hashicorp/terraform-plugin-framework/tfsdk#Provider),
 you need to use the
-[`tfsdk.NewProtocol6Server`](https://pkg.go.dev/github.com/hashicorp/terraform-plugin-framework/tfsdk#NewProtocol6Server)
+[`tfsdk.NewProtocol6ProviderServerWithError`](https://pkg.go.dev/github.com/hashicorp/terraform-plugin-framework/tfsdk#NewProtocol6ProviderServerWithError)
 helper. For example:
 
 ```go
 resource.Test(t, resource.TestCase{
 	PreCheck: func() { testAccPreCheck(t) },
 	ProtoV6ProviderFactories: map[string]func() (tfprotov6.ProviderServer, error) {
-		"example_provider": func() (tfprotov6.ProviderServer, error) {
-			// newProvider is your function that returns a
-			// tfsdk.Provider implementation
-			return tfsdk.NewProtocol6Server(newProvider()), nil
-		},
+		// newProvider is your function that returns a tfsdk.Provider
+		"example_provider": tfsdk.NewProtocol6ProviderServerWithError(newProvider()),
 	},
 	CheckDestroy: testAccCheckExampleResourceDestroy,
 	Steps: []resource.TestStep{

content/plugin/mux/combining-protocol-version-6-providers.mdx

@@ -67,12 +67,8 @@ func main() {
 	ctx := context.Background()
 	providers := []func() tfprotov6.ProviderServer{
 		// Example terraform-plugin-framework providers
-		func() tfprotov6.ProviderServer {
-			return tfsdk.NewProtocol6Server(provider1.New("test")())
-		},
-		func() tfprotov6.ProviderServer {
-			return tfsdk.NewProtocol6Server(provider2.New("test")())
-		},
+		tfsdk.NewProtocol6ProviderServer(provider1.New("test")())
+		tfsdk.NewProtocol6ProviderServer(provider2.New("test")())
 	}
 
 	muxServer, err := tf6muxserver.NewMuxServer(ctx, providers...)
@@ -113,12 +109,8 @@ resource.Test(t, resource.TestCase{
 			ctx := context.Background()
 			providers := []func() tfprotov6.ProviderServer{
 				// Example terraform-plugin-framework providers
-				func() tfprotov6.ProviderServer {
-					return tfsdk.NewProtocol6Server(provider1.New("test")())
-				},
-				func() tfprotov6.ProviderServer {
-					return tfsdk.NewProtocol6Server(provider2.New("test")())
-				},
+				tfsdk.NewProtocol6ProviderServer(provider1.New("test")())
+				tfsdk.NewProtocol6ProviderServer(provider2.New("test")())
 			}
 
 			muxServer, err := tf6muxserver.NewMuxServer(ctx, providers...)

content/plugin/mux/translating-protocol-version-5-to-6.mdx

@@ -57,9 +57,7 @@ providers := []func() tfprotov6.ProviderServer{
 	upgradedSdkProvider.ProviderServer,
 
 	// Example terraform-plugin-framework provider
-	func() tfprotov6.ProviderServer {
-		return tfsdk.NewProtocol6Server(frameworkprovider.New(version)())
-	},
+	tfsdk.NewProtocol6ProviderServer(frameworkprovider.New(version)())
 }
 
 muxServer, err := tf6muxserver.NewMuxServer(ctx, providers...)

content/plugin/mux/translating-protocol-version-6-to-5.mdx

@@ -37,9 +37,7 @@ The following example downgrades a `terraform-plugin-framework` provider.
 ```go
 downgradedFrameworkProvider, err := tf6to5server.DowngradeServer(
 	context.Background(),
-	func() tfprotov6.ProviderServer {
-		return tfsdk.NewProtocol6Server(frameworkprovider.New(version)())
-	},
+	tfsdk.NewProtocol6ProviderServer(frameworkprovider.New(version)())
 )
 ```
 
@@ -81,9 +79,7 @@ resource.Test(t, resource.TestCase{
 			ctx := context.Background()
 			downgradedFrameworkProvider, err := tf6to5server.DowngradeServer(
 				ctx,
-				func() tfprotov6.ProviderServer {
-					return tfsdk.NewProtocol6Server(frameworkprovider.New("test")())
-				},
+				tfsdk.NewProtocol6ProviderServer(frameworkprovider.New("test")())
 			)
 
 			if err != nil {