Replace Salesforce Extension Model created during import

Designer's current Extension Model framework is limiting the ability to be more flexible when modeling and translating metadata through the VDB at runtime and to inject DB-specific metadata (translator) during JDBC Import.

There are also drawbacks from having separate extension models (i.e. The Salesforce Import use-case)

TEIIDDES-905 is providing a new extension model framework that eliminates the need for a separate model.

1) Add "Edit Extended Properties" action and dialog/editor
2) Create a CND (Compact Node Definition) file/string to embed in the model (non-editable)
3) Decorate the model and it's "extended objects" (i.e. tables and columns) to indicate they are "extended"