container: support user defined logs endpoint

[maxux]

This PR allows user to forward container stdout/stderr to external endpoint. Right now, only redis is supported. You can define on container reservation a new field logs which contains information where to push logs:

        "logs": [
          {
            "type": "redis",
            "data": {
              "endpoint": "redis://10.241.0.232:6370",
              "channel": "debug"
            }
          }
        ],

This endpoint is a reachable redis, and channel is a pub/sub where logs will be sent (one line at a time).

[codecov]

Codecov Report

Merging #578 into master will decrease coverage by 0.24%.
The diff coverage is 6.52%.

@@            Coverage Diff             @@
##           master     #578      +/-   ##
==========================================
- Coverage   35.57%   35.33%   -0.25%     
==========================================
  Files          74       74              
  Lines        5374     5419      +45     
==========================================
+ Hits         1912     1915       +3     
- Misses       3189     3229      +40     
- Partials      273      275       +2     

Impacted Files	Coverage Δ
pkg/container/container.go	0.00% <0.00%> (ø)
pkg/provision/converter.go	43.71% <6.66%> (-3.66%)	⬇️
pkg/gedis/converter.go	24.66% <7.69%> (-1.62%)	⬇️
pkg/provision/container.go	60.68% <100.00%> (+0.27%)	⬆️

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[muhamadazmy]

Excellent PR. but I have one comment that requires a change (regarding schema)

[zaibon]

the PR overall looks ok.
I think there is a way to make things a bit simpler though.
Instead of adding a new ContainerLogger interface, we could just use the WithStream method.
This methods takes any io.Writer. This means any new logger implementation should just implement the io.Writer interface.

The result would be something like

mw := io.MultiWriter(
	logFile,
	redisLogger,
       // any other object that implement io.Writer...
)
container.NewTask(ctx,cio.NewCreator(cio.WithStreams(nil, mw, mw)))

[maxux]

Latest implementation use the MultiWriter that @zaibon suggested, reducing amount of code and complexity. Thanks :)

Still some improvement to fix and everything will be updated.

[maxux]

From 0d6d56f commit message:

• Move pkg/logger to pkg/container/logger since logger package are only for container purpose
• Update name of struct inside logger package for shorter names
  • ContainerLoggerConsole -> Console
  • ContainerLoggerFile -> File
  • ContainerLoggerRedis -> Redis
  • NewContainerLoggers -> NewLoggers
  • NewContainerLoggerFile -> NewFile
  • NewContainerLoggerRedis -> NewRedis
  • NewContainerLoggerConsole -> NewConsole
• Update provision to replace endpoint/channel with redis url for stdout and stderr
• Update tfuser to support new provision fields
  • Removing --logs and --channel
  • Adding --stdout and --stderr options
• Argument are now always using redis://host:port/channel format