formulary: migrate fully-scoped formulae names.
formulary: migrate fully-scoped formulae names.

e.g. allow `brew install some/tap/formula` to look that formula up in
another tap if it has been migrated.

Also, add a deprecation message to point people towards the correct
naming.

Linuxbrew/brew,aw1621107/brew,palxex/brew,muellermartin/dist,Homebrew/brew,amar-laksh/brew_sudo,MikeMcQuaid/brew,JCount/brew,konqui/brew,pseudocody/brew,reitermarkus/brew,pseudocody/brew,mahori/brew,mahori/brew,MikeMcQuaid/brew,jmsundar/brew,nandub/brew,sjackman/homebrew,zmwangx/brew,mgrimes/brew,alyssais/brew,jmsundar/brew,rwhogg/brew,reitermarkus/brew,bfontaine/brew,reitermarkus/brew,tonyg/homebrew,bfontaine/brew,mahori/brew,vitorgalvao/brew,reelsense/brew,gregory-nisbet/brew,palxex/brew,zmwangx/brew,muellermartin/dist,MikeMcQuaid/brew,reitermarkus/brew,hanxue/linuxbrew,DomT4/brew,EricFromCanada/brew,nandub/brew,reelsense/brew,ilovezfs/brew,nandub/brew,mgrimes/brew,Homebrew/brew,claui/brew,konqui/brew,vitorgalvao/brew,rwhogg/brew,Linuxbrew/brew,Linuxbrew/brew,sjackman/homebrew,sjackman/homebrew,amar-laksh/brew_sudo,JCount/brew,pseudocody/brew,DomT4/brew,reelsense/brew,ilovezfs/brew,maxim-belkin/brew,konqui/brew,sjackman/homebrew,gregory-nisbet/brew,Linuxbrew/brew,nandub/brew,jmsundar/brew,aw1621107/brew,EricFromCanada/brew,Homebrew/brew,zmwangx/brew,konqui/brew,MikeMcQuaid/brew,maxim-belkin/brew,JCount/brew,EricFromCanada/brew,hanxue/linuxbrew,alyssais/brew,ilovezfs/brew,palxex/brew,vitorgalvao/brew,mgrimes/brew,alyssais/brew,mahori/brew,maxim-belkin/brew,DomT4/brew,amar-laksh/brew_sudo,Homebrew/brew,tonyg/homebrew,claui/brew,claui/brew,tonyg/homebrew,vitorgalvao/brew,gregory-nisbet/brew,EricFromCanada/brew,rwhogg/brew,JCount/brew,claui/brew,aw1621107/brew,bfontaine/brew,DomT4/brew,muellermartin/dist,hanxue/linuxbrew