Add tests for projections / metadata support

[iblazhko]

This PR adds behavioural tests to make sure BullOak can support projections with links to deleted events, and can support streams soft-deleted from EventStore (as opposed to soft deleted by custom event).

There is one test failure that highlights a problem with BullOak.

• Session for empty truncated stream reports IsNewState as false
• Session for empty projection reports IsNewState as true

I think semantically these are the same, and BullOak session should report same IsNewState value (whichever is better by design).

Also this PR cleans up unused files - local EvenStore executable is not needed anymore, neither is the appsettings.json for the integration tests, and there were some leftover .feature.cs files.

[iblazhko]

There is one test failure that highlights a problem with BullOak.

• Session for empty truncated stream reports IsNewState as false
• Session for empty projection reports IsNewState as true

Actually, I think session property IsNewState is a wrong abstraction.

I think we need two separate properties

• IsNewStream - in case we have throwIfNotExists flag set to false this will indicate whether the stream exists
• IsEmptyStream - if this is true, GetCurrentState() will return default state instance