Prompt user to make Brave the default

[fmarier]

Since we are detecting the distro that the user is using, we could either set Brave as the default (after prompting the user), or at least print instructions on how to do that specific to their distro.

e.g.

Your current default browser is: google-chrome
Would you like to make Brave the default? [Y/n]

https://feeding.cloud.geek.nz/posts/set-default-web-browser-debian-ubuntu/ has many of the ways that the default browser can be set.