fix(#730): delete objects that are removed from templates

[MatousJobanek]

The code to be reviewed is in this commit 8630aa6

• when an object is removed from any of the templates, then during the next update it removes the corresponding object from an associated namespace in OS

• the deletion is done by comparing the content of the templates that were used for the update/provisioning of the namespace last time. It takes the version of the namespace and because it represents a commit in tenant repo, then it downloads the content of the template from the corresponding blob. Then it just compares the objects - combination of kind/name/namespace

• introduces a caching mechanism to minimize the number of downloads of the previous version of the templates. The cache contains a record for a particular version and for a particular environment type. The actual target of the cache is list of removed objects

is blocked by #741 as it is built on top of it

Fixes: #730

[codecov]

Codecov Report

Merging #745 into master will increase coverage by 1.45%.
The diff coverage is 82.29%.

@@            Coverage Diff             @@
##           master     #745      +/-   ##
==========================================
+ Coverage   75.15%   76.61%   +1.45%     
==========================================
  Files          37       38       +1     
  Lines        3128     3211      +83     
==========================================
+ Hits         2351     2460     +109     
+ Misses        583      565      -18     
+ Partials      194      186       -8

Impacted Files	Coverage Δ
auth/service.go	73.73% <ø> (ø)	⬆️
toggles/toggles.go	30.61% <ø> (ø)	⬆️
openshift/removed_objects.go	100% <100%> (ø)
controller/convert.go	100% <100%> (ø)	⬆️
jsonapi/jsonapi_utility.go	70.1% <100%> (ø)	⬆️
configuration/configuration.go	71.25% <100%> (ø)	⬆️
migration/migration.go	38.13% <100%> (ø)	⬆️
controller/update.go	69.14% <100%> (ø)	⬆️
controller/tenants.go	63.96% <46.87%> (ø)	⬆️
environment/template.go	89.13% <50%> (+0.72%)	⬆️
... and 31 more

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[fabric8cd]

This PR changes one or more of the template files. These changes are now available for testing: Launch in OpenShift.io and click the update tenant button