Add support for non-URI EventStore connection strings.

[sjp]

What this PR does / why we need it:

When attempting to health check a working EventStore connection, I was always getting an Unhealthy response.

After debugging, I discovered that there is an assumption in the code that the connection string must be a URI. This is not always the case, and the connection string I was using was similar to the following one taken from the EventStore documentation:

var connectionString = "ConnectTo=tcp://admin:changeit@localhost:1113; HeartBeatTimeout=500";

I have added support for connection strings in the format shown above.

Which issue(s) this PR fixes:

Please reference the issue this PR will close: #[issue number]

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

Please make sure you've completed the relevant tasks for this PR, out of the following list:

• Code compiles correctly
• Created/updated tests
• Unit tests passing
• End-to-end tests passing
• Extended the documentation
• Provided sample for the feature

[unaizorrilla]

Hi @sjp

LGTM , fix tests and merge. When a release build finished a new package will be on nuget with 3.0.1