ACL for mcs

[Alevsk]

This PR sets the initial version of the ACL for mcs, the idea behind
this is to start using the principle of least privileges when assigning
policies to users, currently mcsAdmin policy uses admin:* and s3:*, we
are assuming users have access to everything which is not good.

We need to start validating explicitly if users has acccess to an
specific endpoint based on IAM policy actions.

In this first version every endpoint (you can see it as a page to),
defines a set of well defined admin/s3 actions to work properly, ie:

// corresponds to /groups endpoint used by the groups page
var groupsActionSet = iampolicy.NewActionSet(
    iampolicy.ListGroupsAdminAction,
    iampolicy.AddUserToGroupAdminAction,
    //iampolicy.GetGroupAdminAction,
    iampolicy.EnableGroupAdminAction,
    iampolicy.DisableGroupAdminAction,
)

// corresponds to /policies endpoint used by the policies page
var iamPoliciesActionSet = iampolicy.NewActionSet(
    iampolicy.GetPolicyAdminAction,
    iampolicy.DeletePolicyAdminAction,
    iampolicy.CreatePolicyAdminAction,
    iampolicy.AttachPolicyAdminAction,
    iampolicy.ListUserPoliciesAdminAction,
)

With that said, for this initial version, now the sessions endpoint will
return a list of authorized pages to be render on the UI, on subsequent
prs we will add this verification of authorization via a server
middleware.

[bexsoft]

Please run make assets

[cesnietor]

I'm getting this error.

[dvaldivia]

This policy causes the reducer to panic on null returned by the server, avoid NPE

{
    "name": "mcsTestUserAddOnly",
    "Statement": [
        {
            "Action": [
                "admin:CreateUser"
            ],
            "Effect": "Allow",
            "Resource": [
                "arn:aws:s3:::*"
            ]
        }
    ],
    "version": "2012-10-17"
}

[Alevsk]

This policy causes the reducer to panic on null returned by the server, avoid NPE

{
    "name": "mcsTestUserAddOnly",
    "Statement": [
        {
            "Action": [
                "admin:CreateUser"
            ],
            "Effect": "Allow",
            "Resource": [
                "arn:aws:s3:::*"
            ]
        }
    ],
    "version": "2012-10-17"
}

fixed

[dvaldivia]

Can you remove menu groups if not a single options is available?

[cesnietor]

Just some comments, probably here we shouldn't show that Dashboard window also.
Or remove that Access denied

[cesnietor]

Can we remove this logs? or are they needed?

[Alevsk]

@cesnietor @dvaldivia

[bexsoft]

I think we might change the text in README.md to avoid confusions. Also we could add a link to the page where all the privileges list for mcs. Everything else looks good.

[bexsoft]

Please rebase

[Alevsk]

Please rebase

i don't see any new changes

[bexsoft]

LGTM