Add TnsNames support

[ctlemp2018]

At the moment, you can only include one Oracle server in the Oracle node configuration. In production environments, most of the time you have a clustered infrastructure where Oracle can be hosted on two (or more) servers. So the host of the database instance can change because of infrastructure performance or fail).

This could be easily fixed if you allow support in the configuration of the node for the use of TNS names instead of manual server/port/SID configuration.

A combination of the two possible configurations would be ideal, as is possible with all other Oracle client tools.

[juwiefer-btc]

From the code, it seems that this has been implemented silently with pull request #24 a year ago. Simply insert "@" into the Database field and Server and Port are ignored.

There are two issues with this, however:

• This behavior is not documented, as far as I can see.
• The corresponding changes have only been done in lib\, not in the typescript sources in src. I'm not sure how much of a problem this really is.