Fix mkcert addon issues (#62)

[fjmk]

Fixes #62

1. Changes

• added file mkcert.filelist
• error when global flag is not given
• install mkcert binary when version is not current
• better INFO/ERROR messages

2. It runs sudo mkcert --install now. If installed before, you will see the message:

Using the local CA at "/home/frans/.local/share/mkcert" ✨
The local CA is already installed in the system trust store! 👍
The local CA is already installed in the Firefox and/or Chrome/Chromium trust store! 👍

Difficulty in testing addons is that fin is always using $URL_ADDONS_HOSTING/docksal/addons and the master branch. Maybe creating an overide for the repo & branch is an possibility to make it easier for addon development?

[fjmk]

It is possible to test this on a system with a brew installed mkcert:
brew remove mkcert
brew cleanup
fin addon install mkcert -g

The mkcert binary is now installed in $HOME/.docksal/bin/mkcert