Add public form to allow users to add Hebrew dates to shared calendar

[abe-101]

Currently, the only way to add Hebrew dates to the shared calendar is for the user to do it themselves. This can be inconvenient and time-consuming.

A public form would allow users to share a link to the form with others, who can then fill in the form with their Hebrew dates. This would make it much easier for users to add Hebrew dates to the shared calendar, and it would also allow users to collaborate on adding Hebrew dates.