Warn or provide work around for `ENFILE: file table overflow` on macOS

[aaronjudd]

Many (a high number) of new installations of Reaction on macOS are getting Error: ENFILE: file table overflow and are unable to just install and run reaction because of ths

Error: ENFILE: file table overflow, scandir '/Users/aaronjudd/Projects/reaction/packages/gridfs'
    at Error (native)
    at Object.fs.readdirSync (fs.js:808:18)
    at Object.wrapper (/tools/fs/files.js:1586:35)
    at readDirectory (/Users/aaronjudd/.meteor/packages/meteor-tool/.1.4.4_2.

See:

https://github.com/reactioncommerce/reaction/issues/1938 https://github.com/reactioncommerce/reaction/issues/1890

Even though this is a Meteor issue, macOS specific, and there is a work around. Is there a way that we can increase the file limits just for the current reaction run instance?

Maybe check if the file limit is already set high enough, and on macOS, and if not, then prompt user through the changes needed?

This is an open and ongoing issue at https://github.com/meteor/meteor/issues/6952