CS-11: Add a plugin to cache repeated results

[marian13]

What was done as a part of this PR?

• I̶n̶t̶r̶o̶d̶u̶c̶e̶d̶ ̶t̶h̶e̶ ̶̶C̶a̶n̶A̶d̶j̶u̶s̶t̶F̶o̶r̶e̶i̶g̶n̶R̶e̶s̶u̶l̶t̶̶ ̶p̶l̶u̶g̶i̶n̶ ̶t̶h̶a̶t̶ ̶p̶r̶o̶v̶i̶d̶e̶s̶ ̶̶r̶e̶s̶u̶l̶t̶_̶o̶f̶̶.̶
• Introduced the CachesRepeatedResults plugin that caches results that are executed multiple times for one entry service.

Why it was done?

• To introduce a killer feature.

How to test?

• Development: Local Development#tests.

Notes

• This PR is delayed since it is difficult to make a final decision on how exactly to implement this feature.

• Convenient Service has no global context (this is probably one of the main reasons why Convenient Service was born).
  As a result, there is no way to share the results cache between different services like context in React.

• Similar approach as in the Active Record Query Cache is probably the way to go, but it requires management of multithreading issues. Also it is not currently obvious when to create and destroy(refresh) the cache. Should it be delegated to the end user?

• Rails Current Attributes integration can be implemented since it already has some solutions for the problems listed above.

[coveralls]

Pull Request Test Coverage Report for Build 3411166670

• 23 of 23 (100.0%) changed or added relevant lines in 3 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.006%) to 95.86%

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Totals
Change from base Build 3410798751:	-0.006%
Covered Lines:	5325
Relevant Lines:	5555

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💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 3414920048

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 84 of 92 (91.3%) changed or added relevant lines in 11 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.1%) to 95.762%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
lib/convenient_service/rspec/helpers/custom/wrap_method/errors.rb	4	6	66.67%
lib/convenient_service/service/plugins/caches_repeated_results/middleware.rb	8	14	57.14%

Totals
Change from base Build 3413878735:	-0.1%
Covered Lines:	5355
Relevant Lines:	5592

---

💛 - Coveralls

[marian13]

This PR was not supposed to be merged.

GitHub decided to change its status since #17 was merged.

CS-12_cache_return_value_enhancements branch was created from CS-11_plugin_to_cache_repeated_results.

It contained the same amount of commits +1.

That is the reason.