Add service call timeout argument in spawner

[tonynajjar]

This PR exposes the call_timeout of the spawner to be optionally set by the user

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.63%. Comparing base (d55def1) to head (26c79d3).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1808   +/-   ##
=======================================
  Coverage   87.62%   87.63%           
=======================================
  Files         120      120           
  Lines       12217    12224    +7     
  Branches     1093     1093           
=======================================
+ Hits        10705    10712    +7     
  Misses       1123     1123           
  Partials      389      389           

Flag	Coverage Δ
unittests	87.63% <100.00%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
.../controller_manager/controller_manager_services.py	74.62% <100.00%> (ø)
controller_manager/controller_manager/spawner.py	72.22% <100.00%> (+0.44%)	⬆️

... and 5 files with indirect coverage changes

[christophfroehlich]

LGTM, but please rebase/merge on master and update the release_notes and docs as I've done in this PR.