provider/aws: Support Import aws_dynamodb_table (#7352)

There were some changes required to the Read func to get this working.
The initial set of tests showed the following:

```
testing.go:255: Step 1 error: ImportStateVerify attributes not equivalent. Difference is shown below. Top is actual, bottom is expected.

        (map[string]string) {
        }

        (map[string]string) (len=8) {
         (string) (len=8) "hash_key": (string) (len=16) "TestTableHashKey",
         (string) (len=23) "local_secondary_index.#": (string) (len=1) "1",
         (string) (len=36) "local_secondary_index.884610231.name": (string) (len=12) "TestTableLSI",
         (string) (len=52) "local_secondary_index.884610231.non_key_attributes.#": (string) (len=1) "0",
         (string) (len=47) "local_secondary_index.884610231.projection_type": (string) (len=3) "ALL",
         (string) (len=41) "local_secondary_index.884610231.range_key": (string) (len=15) "TestLSIRangeKey",
         (string) (len=4) "name": (string) (len=38) "TerraformTestTable-2710929679033484576",
         (string) (len=9) "range_key": (string) (len=17) "TestTableRangeKey"
        }
```

On investigation, this was telling me that `hash_key`, `range_key`, `name` and `local_secondary_index` were not being set on the Read func

When they were being set, all looks as expected:

```
make testacc TEST=./builtin/providers/aws TESTARGS='-run=TestAccAWSDynamoDbTable_'
==> Checking that code complies with gofmt requirements...
go generate $(go list ./... | grep -v /vendor/)
TF_ACC=1 go test ./builtin/providers/aws -v -run=TestAccAWSDynamoDbTable_ -timeout 120m
=== RUN   TestAccAWSDynamoDbTable_importBasic
--- PASS: TestAccAWSDynamoDbTable_importBasic (20.39s)
=== RUN   TestAccAWSDynamoDbTable_basic
--- PASS: TestAccAWSDynamoDbTable_basic (39.99s)
=== RUN   TestAccAWSDynamoDbTable_streamSpecification
--- PASS: TestAccAWSDynamoDbTable_streamSpecification (50.44s)
PASS
ok  	github.com/hashicorp/terraform/builtin/providers/aws	110.841s
```

builtin/providers/aws/import_aws_dynamodb_table_test.go

@@ -0,0 +1,28 @@
+package aws
+
+import (
+	"testing"
+
+	"github.com/hashicorp/terraform/helper/resource"
+)
+
+func TestAccAWSDynamoDbTable_importBasic(t *testing.T) {
+	resourceName := "aws_dynamodb_table.basic-dynamodb-table"
+
+	resource.Test(t, resource.TestCase{
+		PreCheck:     func() { testAccPreCheck(t) },
+		Providers:    testAccProviders,
+		CheckDestroy: testAccCheckAWSDynamoDbTableDestroy,
+		Steps: []resource.TestStep{
+			resource.TestStep{
+				Config: testAccAWSDynamoDbConfigInitialState(),
+			},
+
+			resource.TestStep{
+				ResourceName:      resourceName,
+				ImportState:       true,
+				ImportStateVerify: true,
+			},
+		},
+	})
+}

builtin/providers/aws/resource_aws_dynamodb_table.go

@@ -34,6 +34,9 @@ func resourceAwsDynamoDbTable() *schema.Resource {
 		Read:   resourceAwsDynamoDbTableRead,
 		Update: resourceAwsDynamoDbTableUpdate,
 		Delete: resourceAwsDynamoDbTableDelete,
+		Importer: &schema.ResourceImporter{
+			State: schema.ImportStatePassthrough,
+		},
 
 		Schema: map[string]*schema.Schema{
 			"arn": &schema.Schema{
@@ -601,6 +604,44 @@ func resourceAwsDynamoDbTableRead(d *schema.ResourceData, meta interface{}) erro
 	}
 
 	d.Set("attribute", attributes)
+	d.Set("name", table.TableName)
+
+	for _, attribute := range table.KeySchema {
+		if *attribute.KeyType == "HASH" {
+			d.Set("hash_key", attribute.AttributeName)
+		}
+
+		if *attribute.KeyType == "RANGE" {
+			d.Set("range_key", attribute.AttributeName)
+		}
+	}
+
+	lsiList := make([]map[string]interface{}, 0, len(table.LocalSecondaryIndexes))
+	for _, lsiObject := range table.LocalSecondaryIndexes {
+		lsi := map[string]interface{}{
+			"name":            *lsiObject.IndexName,
+			"projection_type": *lsiObject.Projection.ProjectionType,
+		}
+
+		for _, attribute := range lsiObject.KeySchema {
+
+			if *attribute.KeyType == "RANGE" {
+				lsi["range_key"] = *attribute.AttributeName
+			}
+		}
+		nkaList := make([]string, len(lsiObject.Projection.NonKeyAttributes))
+		for _, nka := range lsiObject.Projection.NonKeyAttributes {
+			nkaList = append(nkaList, *nka)
+		}
+		lsi["non_key_attributes"] = nkaList
+
+		lsiList = append(lsiList, lsi)
+	}
+
+	err = d.Set("local_secondary_index", lsiList)
+	if err != nil {
+		return err
+	}
 
 	gsiList := make([]map[string]interface{}, 0, len(table.GlobalSecondaryIndexes))
 	for _, gsiObject := range table.GlobalSecondaryIndexes {