Added deprecation notices for /user/current/update

[ocket8888]

What does this PR (Pull Request) do?

• This PR is not related to any Issue

Adds deprecation notices for the /user/current/update to all responses from that endpoint as well as to the documentation.

Which Traffic Control components are affected by this PR?

• Documentation
• Traffic Ops

What is the best way to verify this PR?

Make requests to the /user/current/update endpoint and notice the new warning-level alert indicating its deprecation.
Also, build and read the documentation.

The following criteria are ALL met by this PR

• This PR includes tests OR I have explained why tests are unnecessary
• This PR includes documentation OR I have explained why documentation is unnecessary
• This PR includes an update to CHANGELOG.md OR such an update is not necessary
• This PR includes any and all required license headers
• This PR ensures that database migration sequence is correct OR this PR does not include a database migration
• This PR DOES NOT FIX A SERIOUS SECURITY VULNERABILITY (see the Apache Software Foundation's security guidelines for details)

[asf-ci]

Refer to this link for build results (access rights to CI server needed):
https://builds.apache.org/job/trafficcontrol-PR/4391/

[mhoppa]

I am getting this result when running it

{
    "alerts": [
        [
            {
                "level": "success",
                "text": "User profile was successfully updated"
            }
        ],
        {
            "level": "warning",
            "text": "This endpoint is deprecated, please use 'PUT /api/1.4/user/current' instead"
        }
    ]
}

The deprecation object should be in the alert list

[ocket8888]

Well, actually, it is. The success message is in a sub-list for some reason.

I'll try to figure out why it's doing that.

[ocket8888]

This took hours to figure out. Turns out, [ is VERY different from ( in Perl.

[asf-ci]

Refer to this link for build results (access rights to CI server needed):
https://builds.apache.org/job/trafficcontrol-PR/4440/

[mhoppa]

Works as expected. Looks like an accidental docker change came in so need to revert that.

[asf-ci]

Refer to this link for build results (access rights to CI server needed):
https://builds.apache.org/job/trafficcontrol-PR/4454/