add cache tests

Signed-off-by: georgi.michev georgi.michev@vereign.com

features/distributedCache.feature

-As policy administrator
-I want to have distributed cache feature provided
-So I am able to use cache functionality in my custom policies
-
-Scenario: Working with cache
-Given one policy to set the value in the cache is uploaded to the system
-And the second policy to get the value from the cache is uploaded to the system as well
-When I evaluate policy to set the value in the cache
-And get a successful response
-When I evaluate policy to get the value from the cache
-Then I get a successful response
-And response body is not empty
-
-
-Acceptance criteria:
-- The plugin for rego language to get/set values is ready to use
-- The working example how to use the plugin
-- Green test based on example commited to the system
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