[4.x] Support database cache store tenancy

[lukinovec]

This PR adds the DatabaseCacheBootstrapper. The bootstrapper can be used instead of CacheTenancyBootstrapper for the tenant cache to be saved in the tenant databases instead of keeping it in the central DB.

On bootstrap(), DatabaseCacheBootstrapper sets the database cache store's connection to 'tenant' and deletes the database cache store from the CacheManager's resolved stores -- this forces the manager to resolve a new instance of the database store created with the 'tenant' DB connection on the next cache operation.

On revert(), the bootstrapper reverts the database cache store's connection back to the originally used connection (again, by altering the database cache store's configured connection and deleting the databaes store from the manager's resolved stores).

Solves #852

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.73%. Comparing base (0e223e0) to head (f7aaae0).

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #1290      +/-   ##
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+ Coverage     84.68%   84.73%   +0.04%     
- Complexity     1036     1039       +3     
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  Files           175      176       +1     
  Lines          3043     3052       +9     
============================================
+ Hits           2577     2586       +9     
  Misses          466      466              

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