Add 'Add EmptyDataDecls' code action

[expipiplus1]

Given the below code, GHC suggests turning on EmptyDataDecls:

data Foo

The error message from GHC looks like ‘Foo’ has no constructors (EmptyDataDecls permits this)

It would be great to have this as a code action.

See also #890

[fendor]

Looks like this is a single line change in Pragmas.hs, adding "EmptyDataDecls" to line 96.

[fendor]

Actually, that just compiles for me on ghc-8.2.2, what ghc version is that for?

[expipiplus1]

@fendor I'm using ghc 8.6.4

[fendor]

Still just compiles for me. Very weird.

[fendor]

@expipiplus1 Can you check whether #1187 solves your issue? Because, I can not reproduce that problem at all.

[expipiplus1]

#1187 works perfectly, ++@fendor!