Add Install-DbaFirstResponderKit
Add Install-DbaFirstResponderKit

Adding Install-DbaFirstResponderKit module, which installs/updates these
First Responder Kit stored procedures: sp_Blitz, sp_BlitzWho,
sp_BlitzFirst, sp_BlitzIndex, sp_BlitzCache and sp_BlitzTrace. Monthly
updates are made to them, and it's tedious to get new versions. So a PS
function makes sense. Brent suggested that I add it to dbatools so that
the community can use it too.

kozloski/dbatools,wsmelton/dbatools,sqlpadawan/dbatools,alevyinroc/dbatools,Splaxi/dbatools,dsolodow/dbatools,SirCaptainMitch/dbatools