Add updated field on Action struct

[upgle]

Description

It is related to this PR https://github.com/apache/openwhisk/pull/4646

Since there is no updated field in the Action structure, wsk action get command doesn't show a updated value even though the API passed it.

I think this PR can be merged after the openwhisk-core PR is merged

TEST

Response body received:
{"annotations":[],"exec":{"kind":"nodejs:10","binary":false},"limits":{"concurrency":1,"logs":10,"memory":128,"timeout":60000},"name":"invokerHealthTestAction0","namespace":"whisk.system","parameters":[],"publish":false,"updated":1569485478259,"version":"0.0.1"}
ok: got action invokerHealthTestAction0
{
    "namespace": "whisk.system",
    "name": "invokerHealthTestAction0",
    "version": "0.0.1",
    "exec": {
        "kind": "nodejs:10",
        "binary": false
    },
    "limits": {
        "timeout": 60000,
        "memory": 128,
        "logs": 10,
        "concurrency": 1
    },
    "publish": false,
    "updated": 1569485478259
}

[rabbah]

@upgle should the same change be made to the other entities?

[upgle]

@rabbah yes right, I'll change other entities as well.