Add a Practical Support Mode config

[colinxfleming]

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• What are we trying to do?

Some funds do not deal in pledges and instead just deal in practical support. The pledge stuff doesn't make sense for them, along with some other utilities that are abortion cost specific. To meet their needs we're going to build out a flow. To start this, let's add a Practical Support Mode config.

• What feature or behavior is this required for?
  paring the app down to just useful stuff for practical support funds

• How could we solve this issue? (Not knowing is okay!)
  there's a good approach here for this in #2838 that you can use as a guide!

• Anything else?
  stems from #2174

[mercedesb]

@colinxfleming I could take this on unless there's something else that you'd rather get out the door next

[colinxfleming]

let's do a quick round of archiving first, I'm not sure we've perfectly baked this yet

[elimbaum]

Starting on this (+ #2142, #2174) so we can work on #3017. We already have a Hide practical support option. Now we'd like to add Practical Support Only Mode.

The simplest way to implement this is as a new boolean config, maybe with some checks to make sure we don't conflict with the hiding option. But what about making it a single config? Is that too confusing?

(language TBD)

Practical support options
- Hide practical support
- Practical support ONLY (no pledges)
- Normal mode (practical support + pledges)