Support ARRAY types

[apstndb]

splanter seems to support all Cloud Spanner table column types except ARRAY types.
Ideally, ARRAY types should be supported.

Schama

CREATE TABLE AllTypes (
                     ID STRING(MAX) NOT NULL,
                     BoolValue BOOL,
                     Int64Value INT64,
                     Float64Value FLOAT64,
                     TimestampValue TIMESTAMP,
                     DateValue DATE,
                     StringValue STRING(MAX),
                     BytesValue BYTES(MAX),
                     NumericValue NUMERIC,
                     JSONValue JSON,
                     StringArray ARRAY<STRING(MAX)>,
) PRIMARY KEY(ID);

YAML

---
# Values are need to be encoded as documented.
# https://cloud.google.com/spanner/docs/reference/rpc/google.spanner.v1#google.spanner.v1.TypeCode
- ID: "All_Type_Values"
  BoolValue: true
  BytesValue: "aG9nZQ==" # base64("hoge")
  DateValue: "2022-04-01"
  Float64Value: 3.14159
  Int64Value: 42
  JSONValue: '{"test": 1}'
  NumericValue: "-12345678901234567890123456789.123456789"
  StringValue: "FooBar"
  TimestampValue: "2022-04-01T00:00:00Z"
  # failed to load data to spanner tables: failed to insert records: spanner: code = "InvalidArgument", desc = "client doesn't support type []interface {}"exit status 1
  # StringArray:
  #   - "Foo"
  #   - "Bar"

In this case, it seems to need []interface{}-to-[]string conversion(using INFORMATION_SCHEMA or use reflection?). ARRAY<INT64>, ARRAY<TIMESTAMP>, etc are also should be supported

[uji]

@110y
I tried to support ARRAY types.
I've created a Pull Request and would appreciate a review if you'd like.
#21