Align API behaviour with upstream and return errors on malformed input (#7810)

- Attachments: reject a declared v2 attachment size above the upload limit,
  keep display sizes within the largest unit, and make download links valid
  for 1 minute like upstream.
- Ciphers: moving a personal cipher into an organization needs collection
  write access or full access, like upstream.
- Events: /events/collect only accepts the client event types upstream accepts.
- Client IP: for list headers like X-Forwarded-For, use the rightmost address
  that isn't in IP_HEADER_TRUSTED_PROXIES, reading every occurrence.
- Prelogin: unknown emails get stable KDF settings from upstream's list.
- Login with device: an auth request can be used for one login, like upstream.
- Directory Connector import: never revokes, restores or removes Owners,
  like upstream.
- SSO: check the PKCE verifier again when the code exchange is reused during
  2FA, and accept the same redirect URIs as upstream (desktop localhost
  callback for AppImage and dev builds, CLI on ports 8065-8070).
- Identity: send the merged master password policy in the 2FA response and
  use PascalCase policy keys in identity responses, like upstream.
  Organization API key login no longer needs device fields. Recovery code
  login normalises the code, uses upstream's error message, logs a failed 2FA
  event and sends a "two-step login recovered" email.
- Add GET /api/accounts/keys.
- Return errors instead of panicking on malformed event dates, cipher data,
  key rotation cipher ids, bulk confirm entries and YubiKey OTPs.

src/static/templates/email/recover_twofactor.html.hbs

@@ -0,0 +1,26 @@
+Two-Step Login Recovered From {{ip}}
+<!---------------->
+{{> email/email_header }}
+<table width="100%" cellpadding="0" cellspacing="0" style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 16px; color: #333; line-height: 25px; -webkit-font-smoothing: antialiased; -webkit-text-size-adjust: none;">
+   <tr style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 16px; color: #333; line-height: 25px; -webkit-font-smoothing: antialiased; -webkit-text-size-adjust: none;">
+      <td class="content-block" style="font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 16px; color: #333; line-height: 25px; margin: 0; -webkit-font-smoothing: antialiased; padding: 0 0 10px; -webkit-text-size-adjust: none;" valign="top">
+         Two-step login on your account has been disabled by using the account's recovery code.
+      </td>
+   </tr>
+   <tr style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 16px; color: #333; line-height: 25px; -webkit-font-smoothing: antialiased; -webkit-text-size-adjust: none;">
+      <td class="content-block" style="font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 16px; color: #333; line-height: 25px; margin: 0; -webkit-font-smoothing: antialiased; padding: 0 0 10px; -webkit-text-size-adjust: none;" valign="top">
+         <b>Date:</b> {{datetime}}
+      </td>
+   </tr>
+   <tr style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 16px; color: #333; line-height: 25px; -webkit-font-smoothing: antialiased; -webkit-text-size-adjust: none;">
+      <td class="content-block" style="font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 16px; color: #333; line-height: 25px; margin: 0; -webkit-font-smoothing: antialiased; padding: 0 0 10px; -webkit-text-size-adjust: none;" valign="top">
+         <b>IP Address:</b> {{ip}}
+      </td>
+   </tr>
+   <tr style="margin: 0; font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 16px; color: #333; line-height: 25px; -webkit-font-smoothing: antialiased; -webkit-text-size-adjust: none;">
+      <td class="content-block last" style="font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; box-sizing: border-box; font-size: 16px; color: #333; line-height: 25px; margin: 0; -webkit-font-smoothing: antialiased; padding: 0; -webkit-text-size-adjust: none;" valign="top">
+         If you did not perform this action, you should immediately take steps to secure your account.
+      </td>
+   </tr>
+</table>
+{{> email/email_footer }}