Default for fetch dependencies should be "off"

[marcandre]

Automatic fetching of the dependencies in the background is problematic for many people (e.g. here) and may be even more problematic with the improved semantic recompilation of upcoming Elixir 1.13, as I explain in this issue.

It would be wise to turn this setting off by default, at the very least for new users.

[axelson]

Hi @marcandre! Thanks for the report! This is something that I've been thinking about recently. I agree that we should turn the default to off.