Feature Request: Set default extraction methods

## Type

- [ ] General question or discussion
- [x] Propose a brand new feature
- [ ] Request modification of existing behavior or design

## What is the problem that your feature request solves
It's annoying to have to click the select/option list every time. Friend computer deals with this, please.

## Describe the ideal specific solution you'd want, and whether it fits into any broader scope of changes
Global defaults, user override, applied when presenting the UI, so as to not have any effect on API / mechanized use.

## What hacks or alternative solutions have you tried to solve the problem?
Here's a Violentmonkey script that seems to work.
```javascript
// ==UserScript==
// @name Default Archivebox methods
// @namespace Violentmonkey Scripts
// @match https://archivebox.example.com/add/*
// @grant none
// @version 1.0
// @author -
// @description 2024-05-22 09:18:57
// ==/UserScript==
default_methods = [
"favicon",
"singlefile",
"readability",
"title",
]

node = document.querySelector('#id_archive_methods');
if (node) {
[...node.children].forEach(
o => o.selected = default_methods.find(x => x == o.value)
)
}
```

## How badly do you want this new feature?

- [ ] It's an urgent deal-breaker, I can't live without it
- [ ] It's important to add it in the near-mid term future
- [x] It would be nice to have eventually

---

- [x] I'm willing to contribute [dev time](https://github.com/ArchiveBox/ArchiveBox#archivebox-development)
- [x] I like ArchiveBox so far / would recommend it to a friend
- [ ] I've had a lot of difficulty getting ArchiveBox set up
(nitpick: I would've liked the choice of public archive vs. login-to-see-anything more upfront. Idc if it's a bit involved to set up, (it's not) but the remark that it can be deployed in 'private mode' should be easier to find)

Start at the add-page UI and inspect the #id_archive_methods selector, using the provided Violentmonkey script as the described behavior. The feature is done when global defaults and a user override apply while presenting the UI, without affecting API or other mechanized use.

Written by the indexing model from the issue text.