Implement IEquatable interface

Intended for equality checks, this interface uses
a non-virtual interface idiom.
Implement IPost interface
Implement Post class
Change unit tests architecture

This change enables multi-test suite (multi-file) simultaneous
testing.
Add unit tests for the Post class
Create a Person view and Person window

Intended to show information about a single Person.
Create enums needed by the Person entity
Implement IPerson interface
Implement Person class
Add unit tests for the Person class
Implement post sender and receivers
Implement person posts

Add forward declaration for both person and post
Create a pointer comparison template function
Merge branch 'dev' of https://github.com/aleksandersmierciak/Qt-DbWorkbench into dev
Make project depend on MariaDb and MongoDb drivers

Beginning with this commit, the project requires both
MariaDb C++ driver and MongoDb C++ driver shared libraries
to be present in the standard (system) path.
Implement database connection parameters class
Implement abstract database connector class
Implement MariaDb connector stub with include
Implement MongoDb connector stub with include