Senior destinations banner

[alanzhu0]

Feature description

• tjToday requests a banner for announcing their form for filling out senior college destinations for publication in the senior tjToday issue.
• Create a banner on the Ion dashboard that is visible only to seniors, and which contains a bit of text and has a link to tjToday's Google form (contact me on mattermost for info on text and form).

Rationale for adding feature

• I think this is sufficiently important to warrant a banner

Suggested implementation(s) (if applicable)

• A similar feature exists for the annual tjSTAR ribbon. See: https://github.com/tjcsl/ion/blob/a6ccf4b098de7253d95419da15db36ff80899587/intranet/templates/special/tjstar_ribbon.html. Enable it and see what it looks like, and create something similar. There does not need to be a countdown.
• I would suggest creating variables in settings.py called something like ENABLE_SENIOR_DESTS_BANNER and SENIOR_DESTS_BANNER_FORM_LINK, and activating the banner based on the first variable. Again see the tjSTAR logic.

This is a time-sensitive issue that needs to be done quickly as tjToday needs the info soon. Therefore there will be a deadline for attempting this feature: working draft of code due 4/18, final reviews and deployment 4/20 (this is end of spring break). This should be a pretty straightforward and simple feature though.