Refactorings/exterminate statics

[dseurotech]

Brief description of the PR.
Removes most static variables and manual singletons, in favour of a more pervasive Dependency Injection usage.

Related Issue
This PR fixes/closes 3266

Description of the solution adopted

Exterminating Statics.pdf

Any side note on the changes made

• A lot of code cleanups
• Reworked the structure of data store classes (iteraction with Elastic Search)

[codecov]

Codecov Report

Attention: 741 lines in your changes are missing coverage. Please review.

Comparison is base (1d45940) 0.00% compared to head (b8e989e) 21.18%.
Report is 4 commits behind head on develop.

Additional details and impacted files

@@              Coverage Diff               @@
##             develop    #3837       +/-   ##
==============================================
+ Coverage           0   21.18%   +21.18%     
- Complexity         0       10       +10     
==============================================
  Files              0     1938     +1938     
  Lines              0    41181    +41181     
  Branches           0     3780     +3780     
==============================================
+ Hits               0     8724     +8724     
- Misses             0    32051    +32051     
- Partials           0      406      +406     

Files	Coverage Δ
...emis/plugin/security/setting/BrokerSettingKey.java	0.00% <ø> (ø)
...mmons/rest/filters/settings/RestFiltersModule.java	100.00% <100.00%> (ø)
...stractKapuaConfigurableResourceLimitedService.java	0.00% <ø> (ø)
...a/commons/core/ServiceModuleJaxbClassProvider.java	0.00% <ø> (ø)
...e/kapua/commons/crypto/setting/CryptoSettings.java	100.00% <ø> (ø)
...va/org/eclipse/kapua/commons/event/ServiceMap.java	14.28% <ø> (ø)
.../eclipse/kapua/commons/jpa/EntityCacheFactory.java	100.00% <100.00%> (ø)
...e/kapua/commons/jpa/KapuaEntityManagerFactory.java	54.34% <100.00%> (ø)
...pse/kapua/commons/jpa/NamedEntityCacheFactory.java	100.00% <100.00%> (ø)
.../kapua/commons/liquibase/KapuaLiquibaseClient.java	80.39% <100.00%> (ø)
... and 146 more

... and 1782 files with indirect coverage changes