spike: JavaExecGenerator uses ubi8/openjdk-11 always

[manusa]

This is PoC PR intended for review of options regarding base image replacements (#183)

What this PR accomplishes is the use of registry.access.redhat.com/ubi8/openjdk-11 image for all build strategies.
The main advantage for this is the reduced complexity in maintenance, as configuration should only deal with one image type.

We're also replacing 2 different fabric8 maintained images for a single community-driven image.

In order to be able to use the s2i builder image both as a builder image and as a runtime image is by providing the packaged artifacts in the specific directory for s2i assembly (/tmp/src/deployments). And by adding the COPY statement from deployments to /deployments in the generated Dockerfile.

[codecov]

Codecov Report

Merging #203 into master will increase coverage by 0.00%.
The diff coverage is 83.33%.

@@            Coverage Diff            @@
##             master     #203   +/-   ##
=========================================
  Coverage     26.27%   26.28%           
  Complexity     1589     1589           
=========================================
  Files           350      350           
  Lines         18296    18293    -3     
  Branches       2808     2808           
=========================================
+ Hits           4807     4808    +1     
+ Misses        12931    12927    -4     
  Partials        558      558           

Impacted Files	Coverage Δ	Complexity Δ
...be/openliberty/generator/OpenLibertyGenerator.java	75.00% <80.00%> (+7.50%)	5.00 <1.00> (ø)
...se/jkube/generator/javaexec/JavaExecGenerator.java	83.16% <100.00%> (+0.16%)	22.00 <0.00> (ø)

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[sonarcloud]

Kudos, SonarCloud Quality Gate passed!

0 Bugs
0 Vulnerabilities (and 0 Security Hotspots to review)
0 Code Smells

100.0% Coverage
0.0% Duplication

[rohanKanojia]

@manusa : Is this ready for review?

[manusa]

This is closed by #205.

It was a PoC showcasing how to use unmodified community-based upstream images.

#205 approach is preferred because 100 MiB are stripped off of the upstream image and not much maintenance is required since it's based in community maintained CEKit modules.