Submission Terms: add a submission address

[yolile]

Currently, the extension description says:

Adds a submission terms object to the tender and lot objects, to describe how, when and where the tenderers must submit their bids.

However, the extension doesn't have a field for setting where the bid should be sent if they are not electronic.

In countries like Uruguay (example) and Paraguay (example), this information is currently modeled in submissionMethodDetails as semi-structured text, but it would be better to have a place to put the structured information, similar to the bidOpening extension, but for the bid submission.

[jpmckinney]

Sounds good!

cc @ColinMaudry