Consolidate apple/ios utilities used by different plugins

- current icloud user
  - `icloud_account_id` (email address)
  - `icloud_account_dsid` (numeric id)
  - `icloud_account_display_name` (full name)
- ios timestamps
  - `ios_timestamp_to_unix`
  - `unix_to_ios_timestamp`
- local contacts
- phone number