Add support for Firebird

[n-riesco]

I think this one is easily doable. A quick search shows there is already a pure Javascript client for Firebird: https://www.npmjs.com/package/node-firebird

I'm going to label this one as community and good first issue.

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Related:

• http://www.firebirdsql.org/
• https://github.com/FirebirdSQL/firebird
• https://www.npmjs.com/package/node-firebird
• https://www.npmjs.com/package/firebird