✨ Dask gateway: add traefik proxy for http(s) access

[sanderegg]

What do these changes do?

• add a traefik proxy in the dask-gateway docker-compose
• the idea is to provide https access

Related issue/s

• related to AppTeam Std Simulations on S4L/AWS osparc-issues#885
• related to M1-12 Maintenance and DevOps osparc-issues#675
• related to Dask clusters issues #2945

How to test

[codeclimate]

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[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

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[codecov]

Codecov Report

Merging #4039 (e3e13de) into master (935557a) will decrease coverage by 2.7%.
The diff coverage is n/a.

@@            Coverage Diff            @@
##           master   #4039      +/-   ##
=========================================
- Coverage    83.0%   80.4%    -2.7%     
=========================================
  Files         946       8     -938     
  Lines       40979     358   -40621     
  Branches      851       0     -851     
=========================================
- Hits        34034     288   -33746     
+ Misses       6736      70    -6666     
+ Partials      209       0     -209     

Flag	Coverage Δ
integrationtests	80.4% <ø> (+34.4%)	⬆️
unittests	?

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