Fix parsing error when there are no parens around = in a type alias declaration

[jfmengels]

There was an issue with parsing type alias declarations when there was no spacing on either side of the = sign.

-- Succeed to parse
type alias A = ()
-- Fail to parse
type alias A= ()
type alias A =()

Example of this happening in an Ellie: https://ellie-app.com/cJJBxZd4gkga1

This is also the case in v8, so we'll need to backport this to master.

[MartinSStewart]

I looked at all the places "=" shows up and found that it's also incorrect for LetDestructuring. I went ahead and fixed that. It looks like it's also incorrect for destructuringDeclaration in Declaractions.elm but I think this can be left alone because destructuring isn't possible for top level declarations so really that whole function should be removed at some point.

[jfmengels]

Nice 👍
Your changes look good to me. Are you okay with merging this then?

[MartinSStewart]

Sounds good to me