TrainsLogger semantic segmentation example

[bmartinn]

Following the discussion at #1057

Description:
Add TrainsLogger Example to the semantic segmentation tutorial.

Check list:

• New tests are added (if a new feature is added)
• New doc strings: description and/or example code are in RST format
• Documentation is updated (if required)

[vfdev-5]

@bmartinn thanks for the PR !
What we plan to do next from our side

• update these examples with our recent distributed module and coming one
• setup an online Trains server (as discussed in a comment and with Moses)
• run thoses experiments on various infras with logging to the online server.

cc @sdesrozis

[sdesrozis]

@bmartinn Thank you for this excellent improvement of our reference segmentation usecase 👍🏻 let’s see the next 😊

[bmartinn]

@sdesrozis any idea why the TPU test is failing? (is it related to the PR?)

[sdesrozis]

No, it’s not related. Let’s restart.

[sdesrozis]

@bmartinn Thank you!!