[danger] Add a check for changes that affect multiple components. (#4155)
[danger] Add a check for changes that affect multiple components. (#4155)

Adds a new check to our Danger CI that provides a warning if a PR is affecting the source code of multiple components simultaneously.
material-components/material-components-ios,material-components/material-components-ios,material-components/material-components-ios,randallli/material-components-ios,randallli/material-components-ios,randallli/material-components-ios,randallli/material-components-ios,material-components/material-components-ios,randallli/material-components-ios,material-components/material-components-ios,randallli/material-components-ios