Made recent searches be stored per-account

[EricBAndrews]

Checklist

• I have read CONTRIBUTING.md
• I have described what this PR contains
• This PR addresses one or more open issues that were assigned to me:
  - Slack
• If this PR alters the UI, I have attached pictures/videos

Pull Request Information

Changed how recent searches are handled persist them per-account. This involves:

• Changing loadRecentSearches to reloadRecentSearches, which will clear the value and reload using the current account hash (it's only called in one place on .onAppear, so this shouldn't break anything)
• Persisting recent searches as a map of accountHash to list of ContentModelIdentifier

Recent.Search.Per.Account.PR.mov

[mormaer]

I'm not sure we should be storing an account based value on the APIClient as the client needs to work without accounts too (guest mode).

It's also stored on the client only to be read back out to pass as an argument elsewhere which seems odd.

Would it be better to simply make the recent search tracker / persistence take something like the instance URL as an argument to use as the key?

The communities and user ids will be correct on the same instance for example, even if someone had multiple accounts on the same instance 🤔

[mormaer]

Looks good - there's a test failure for a mismatch of Int instead of String, so I disabled auto-merge in case this approval made it merge when I hit enter 😅