Allows custom setting the formatter

[lafirest]

Description

The low-level formatting plugin erlang_ls relies on supports some formatters, maybe it would be good to expose them into the configuration.

This PR added a new configuration section with an option to specify the formatter

Fixes # .

[plux]

Thanks for your contribution, @lafirest .

Ironically CI complained about code formatting. :)
You can fix this by running rebar3 fmt and committing the changes.

[lafirest]

Thanks for your contribution, @lafirest .

Ironically CI complained about code formatting. :) You can fix this by running rebar3 fmt and committing the changes.

Sorry, I thought I have formatted, I have fixed this

[plux]

Thanks for your contribution @lafirest !