ApiAnnotations : preserve parens in GADTs
A cleanup in 7f418acf accidentally discarded some parens in ConDeclGADT.
Make sure these stay in the AST in a usable format.
Also ensure the AnnLolly does not get lost in a GADT.
Note: for ease of cherry-picking, this diff was created on the ghc-9.0 branch as c83ac326, and then adapted for master. The linear types annotations are slightly different for each.