composer server ssl install CLI does not install the root certificate if mckert is already installed

[tomjn]

The composer server ssl install command implies that it will install the SSL certificate:

  	ssl install                   Installs and trusts Root Certificate Authority

But this does not always happen.

If mkcert is already installed no attempt is made to install a root certificate because the install command code calls return, so no attempt is made. This can lead to certificates being served that aren't accepted by the browser

[tomjn]

To get around this these undocumented steps were needed:

composer server ssl generate mysite.local
composer server ssl exec -- -install