accounts/email: provide realName option for alias

[eum3l]

Description

Provide options for setting realName in accounts.email.accounts.*.aliases.

Checklist

• Change is backwards compatible.

• Code formatted with ./format.

• Code tested through nix-shell --pure tests -A run.all or nix develop --ignore-environment .#all using Flakes.

• Test cases updated/added. See example.

• Commit messages are formatted like

  {component}: {description}
  
  {long description}
  

  See CONTRIBUTING for more information and recent commit messages for examples.

Maintainer CC

@d-dervishi