[#469] Add base implementation for tickets

Description

Adds tickets implementation.

Left for future work:

• #585 (closed) (probably should be implemented quickly, since this is gonna be another breaking change)
• !835 (merged) - helpers for working with tickets.

Also created indigo#46, and this issue actually seems like a problem because it is not obvious how much work will be required to make Indigo work in the presence of Dupable constraint.

Related issue(s)

Resolves #469 (closed)

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