Add skill for laravel boost

[punyflash]

This PR adds skill for LunarPHP that may be used in Laravel Boost:

php artisan boost:add-skill lunarphp/lunar

[glennjacobs]

Thanks @punyflash

There's some opinionated bits in this, e.g. Laravel Sail for example, which it probably shouldn't have.

[wychoong]

only have a few suggestions

• installation guide seems redundant as the skill wont be available before install
• break the skills into references like how laravel skills are, so can go in-depth in future
• might be great to incorporate https://docs.lunarphp.com/1.x/guides guides, how to avoid duplicate effort in package & docs