Update ESLint rules to always add a blank line after the copyright header

[hmhealey]

I forget why, but I decided to check if eslint-plugin-header had an option to always add a blank line after the header. Turns out that it does!

I look forward to not having to be tempted to change this every time I see one of these 355 files that is missing that line

Release Note

NONE

[M-ZubairAhmed]

That being said i have few other empty line nits, i should look into 😛 will run by the team once i compile those.