Add support for Oracle connections string to support failover setups

[mmattel]

What Needs to be Documented?

New installation options for Oracle, see owncloud/core#36489

Where Does This Need To Be Documented?

Admin/Installation

Why Should This Change Be Made? (Optional)

New option

What Type Of Content Change Is This? (Optional)

• New Content Addition
• Old Content Deprecation
• Existing Content Simplification
• Bug Fix to Existing Content

Which Manual Does This Relate To? (Optional)

• Admin Manual
• Developer Manual
• User Manual
• Android
• iOS
• Branded Clients
• Desktop Client
• Other

@settermjd @DeepDiver1975