add password and banner to draft site

copy some CI aspects of setup for website. In particular, these Issues:

• password setup for draft site here
• adding a banner to the draft site here

Use this JB feature in the *.yml file (example here).

changed due date to August 29, 2023

changed milestone to %Backend book support: Phase 1

added IT status::planned labels

assigned to @cjungbacker

mentioned in issue #35 (closed)

the banner part of this Issue should be applied to Issue #35 (closed)

perhaps this issue should be split in 2, since the password and banner are separate?

added status::wip label

removed status::planned label

mentioned in merge request !78 (merged)

closed with merge request !78 (merged)

mentioned in commit ba9c8245

removed status::wip label