Implement sem status operation to debug dead-lock cases

[fgalan]

To implement a new operations (e.g. /sem) which would return

{
    "request" : { "status": "open", "time": 0 },
    "request" : { "status": "closed", "time": 0.002 },
    "transaction" : ...
    "subCache" : ...
    "connectionContext" : ...
    "timeStat" : ...
}

If status is "open", then time is always 0. If status is "closed" then time is the time that the sem has been closed.

If providing blocking times is complicated, then just open/close information for each sem would be ok.

[kzangeli]

Only status in the list of sem-ifnfo so far.

In the future, more info should be added:

• owner, in case 'taken': who took it?
• purpose, in case 'taken': for what purpose?
• errors, number of errors for this semaphore
• waitTime, total waiting-time for this semaphore
• count, number of times the semaphore has been taken

[fgalan]

waitTime, total waiting-time for this semaphore

Not really... waitTime on sem is already in /statitics ops. What would be interesting in /sem would be a metric (named waitTime or other) that:

• If the sem is "free" is always "0"
• If the same is "taken" is the time that it has been taken.

This is useful to check if a sem is never released (i.e. if we always see it in "taken" state and the time metric dont't stop to grow).

[fgalan]

Partically implemented in PR https://github.com/telefonicaid/fiware-orion/pull/2234.

I understand that with that implementation target for 1.3.0 is covered. Thus, moving out of milestone.