formula_installer: skip linking formulae with already installed casks.
formula_installer: skip linking formulae with already installed casks.

If you have the `emacs` or `docker` formulae and casks both
installed the formula will fail to link. Skip trying to link the formula
if the cask is already installed.

Fixes https://github.com/Homebrew/homebrew-core/issues/36310.

mahori/brew,JCount/brew,nandub/brew,claui/brew,EricFromCanada/brew,MikeMcQuaid/brew,vitorgalvao/brew,mahori/brew,JCount/brew,reitermarkus/brew,Homebrew/brew,reitermarkus/brew,konqui/brew,konqui/brew,nandub/brew,Homebrew/brew,sjackman/homebrew,claui/brew,JCount/brew,claui/brew,EricFromCanada/brew,sjackman/homebrew,JCount/brew,nandub/brew,reitermarkus/brew,vitorgalvao/brew,MikeMcQuaid/brew,mahori/brew,claui/brew,sjackman/homebrew,MikeMcQuaid/brew,konqui/brew,Homebrew/brew,Homebrew/brew,nandub/brew,mahori/brew,konqui/brew,sjackman/homebrew,EricFromCanada/brew,reitermarkus/brew,EricFromCanada/brew,vitorgalvao/brew,MikeMcQuaid/brew,vitorgalvao/brew