Can't write to H5T_ARRAY datasets

Test code attempting to create and write to an H5T_ARRAY dataset (originally written in `value_test.py`):

```
def testPutArray(self):
headers = helper.getRequestHeaders(domain=self.base_domain)
req = self.endpoint + "/"

# Get root uuid
rsp = self.session.get(req, headers=headers)
self.assertEqual(rsp.status_code, 200)
rspJson = json.loads(rsp.text)
root_uuid = rspJson["root"]
helper.validateId(root_uuid)

datatype = {
"class": "H5T_ARRAY",
"base": {
"class": "H5T_INTEGER",
"base": "H5T_STD_I32LE"
},
"dims": [6]
}

payload = {
"type": datatype,
"shape": 1,
}

req = self.endpoint + "/datasets"
rsp = self.session.post(req, data=json.dumps(payload), headers=headers)
self.assertEqual(rsp.status_code, 201) # create dataset

rspJson = json.loads(rsp.text)
array_dset_uuid = rspJson["id"]
self.assertTrue(helper.validateId(array_dset_uuid))

# verify the shape of the dataset
req = self.endpoint + "/datasets/" + array_dset_uuid
rsp = self.session.get(req, headers=headers)
self.assertEqual(rsp.status_code, 200) # get dataset
rspJson = json.loads(rsp.text)
shape = rspJson["shape"]
self.assertEqual(shape["class"], "H5S_SIMPLE")

# link new dataset as 'array_type_dset'
name = "array_type_dset"
req = self.endpoint + "/groups/" + root_uuid + "/links/" + name
payload = {"id": array_dset_uuid}
rsp = self.session.put(req, data=json.dumps(payload), headers=headers)
self.assertEqual(rsp.status_code, 201)

# read initial values
req = self.endpoint + "/datasets/" + array_dset_uuid + "/value"
rsp = self.session.get(req, headers=headers)
self.assertEqual(rsp.status_code, 200)
rspJson = json.loads(rsp.text)
self.assertTrue("value" in rspJson)
self.assertTrue(np.array_equal(rspJson["value"][0], np.zeros(6)))

# write to the array
value = [[1, 2, 3, 4, 5, 6]]
payload = {"value": value}
req = self.endpoint + "/datasets/" + array_dset_uuid + "/value"
rsp = self.session.put(req, data=json.dumps(payload), headers=headers)
self.assertEqual(rsp.status_code, 200) # write value

# read back the value
rsp = self.session.get(req, headers=headers)
self.assertEqual(rsp.status_code, 200)
rspJson = json.loads(rsp.text)
self.assertTrue("value" in rspJson)
self.assertTrue(np.array_equal(rspJson["value"], value))
```

This fails at the 200 response code assert after trying to write to the dataset with `AssertionError: 400 != 200`.

Log output from the service node:
```
REQ> PUT: /datasets/d-5b64a0fe-22b9a690-5c8a-aeba16-834c57/value [/home/test_user1/hsds_test/valuetest/20230822T165739_378063Z]
DEBUG> num tasks: 4 active tasks: 4
DEBUG> validateUserPassword username: test_user1
DEBUG> looking up username: test_user1
DEBUG> user password validated
DEBUG> PUT value - request_type is json
INFO> getObjectJson d-5b64a0fe-22b9a690-5c8a-aeba16-834c57
DEBUG> found d-5b64a0fe-22b9a690-5c8a-aeba16-834c57 in meta_cache
DEBUG> PUT Value selection: (slice(0, 1, 1),)
DEBUG> selection shape: [1]
DEBUG> selection num elements: 1
WARN> input data doesn't match selection
```