Add To-Do "Snooze until next week" option

Overview

On the To-Do List (/dashboard/todos), when you click the "Snooze…" button, it currently shows 3 presets ("For one hour", "Until later today", and "Until tomorrow") along with "Until a specific time and date".

Currently all of the presets are short-term (within 24 hours) — it would be helpful to have a longer preset option, such as "Until next week", to handle lower-priority items.

Rationale

On #17712 (comment 2296819306), @nickleonard said:

The rationale for why I think this is useful is that "Next week" gives enough space that users can clear less pressing items. "Tomorrow" as the max means having to defer items potentially 5 times in a work week, this can reduce that to 1 time per week, until it's relevant. This is useful for "when time allows" type items.

On #17712 (comment 2297154851), @ameliabauerly said:

We made our best guess as to what appropriate snoozing time periods might be but, I'd definitely be open to increasing the time interval between the options. After reading your feedback and Sam's feedback, I would tend to agree, the current options are all very close together (temporally), and so close together that they are probably nearly identical, from a task management POV. I guess we can wait to see what others say but, I'd definitely be open to adjusting these options, and replacing one with next week. Thank you for this feedback!

On #17712 (comment 2302213972), @thutterer said:

+1 for a fixed (non-custom) "Next week" option that snoozes to the following Monday morning.

I would use this all the time. Slack has that option, and it is really useful. I usually then on Monday morning prioritize these items again, snoozing them within Monday, or "Tomorrow".

Proposed behavior

On #17712 (comment 2296819306), @nickleonard said:

The way I think of this "Next week" would always resolve to Monday of the next week, and can follow the timing logic of "tomorrow" as always 0800. This is the same as Slack's "next week" option.