Create Data Access Layer for Cosmos SQL API

[EliuX]

In this PR we create a new Data Access Layer (DAL) for Cosmos DB. It also makes room for other projects, namely the planned time-tracker-events, to use this DAL as well. Therefore, all implementations of the DAL were moved out to a new namespace called commons. This way any resource or utility that is common to multiple applications would be stored in this namespace.
The new DAL allows:
To handle items with a repository:

• Create items
• Partial update items
• Completely update items
• Delete items
• find one item
• find multiple items: allows pagination

To handle containers:

• Create a container, based on a definition.
• Delete a container

Tests were created to cover 100% of all the functional code of these new features.