Draft: Add Model\Account class to handle accounts

This is a rather large set of patches, that add an Account model to handle all interactions with the accounts database table. This will hopefully make it a bit easier to reason about where account information is modified, instead of having direct database queries spread throughout the code.

The idea is also that this will be a model for turning other database table objects into model objects.

The following modules have been updated to use the new API:

• Zotlabs\Lib\Libzot::site_info
• Zotlabs\Module\Admin\Account_edit
• Zotlabs\Module\Regate

For the Account_edit module, this also includes significantly improved input validation, and refactoring to make the code more robust and simpler.

I've also marked the following functions from include/account.php as deprecated:

• get_account_by_id: Replaced by Zotlabs\Model\Account::get_by_id().
• account_total: Replaced by Zotlabs\Model\Account::count()

As there's still code (and potentially addons) that use these functions, we can't just remove them cold quite yet.

Note that Zotlabs\Model\Account::get_by_id() returns an Account object, not an associative array of key/value pairs. This allows for better type checking and moving the type checking to the class, instead of spread around and repeated throughout the code base.

This patch also fixes #1876 (CVE-2024-51443).