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ARROW-17322: [Docs] Documenting issue lifecycle for bugs and feature requests (#13781)

These changes aim to document the issue lifecycle - how to create new issues (largely already existed) as well as how to engage with and understand issue state later on. This also serves to document proposed processes:

1. Assigned issues idle more than 90 days may be unassigned (discussed and approved on ML)
2. Unassigned issues in "In Progress" status should be set to "Open"
3. Establishing consistent usage of Status and Resolution fields.

Authored-by: Todd Farmer <todd@fivefarmers.com>
Signed-off-by: Antoine Pitrou <antoine@python.org>