Support symfony/console 5.x

[stevenrombauts]

Add initial support for symfony/console ^5.0

Todo's:

• Update folioshell too

[stevenrombauts]

@yiendos Would you mind giving this a go on your end too? This should solve an issue Waseem is having installing the console in a Valet environment. You can try it directly on the box with:

# Temporarily remove folioshell because it's not updated yet
composer global remove foliolabs/folioshell
# Install this branch
composer global require joomlatools/console:dev-feature/129-symfony5 
# Now upgrade symfony/console
composer global require symfony/console:^5.0
# Verify with
composer global show | grep symfony/console

Then make sure all commands still work. These changes are very minimal so no need to run through every command explicitely.

[stevenrombauts]

@yiendos Note, if this works OK we can add this to the 1.5.9 tag along with #125