[WIP] Completion support (#227)

* Initial implementation of completion support

* Add fuzzy to set of additional dependencies in 8.8

* Fix test

* Work a bit more on completion

* Attempt at getting completions from last good tckd module

* Revert "Attempt at getting completions from last good tckd module"

This reverts commit 04ca13b.

* "useWithStale" everywhere

* Some suggestions by @cocreature

* Adjust positions in the document

* Start working on tests

* Fix compilation problem

* Fix tests

* Better type tests

ghcide.cabal

@@ -39,6 +39,7 @@ library
         deepseq,
         directory,
         extra,
+        fuzzy,
         filepath,
         hashable,
         haskell-lsp-types == 0.19.*,
@@ -96,6 +97,8 @@ library
     include-dirs:
         include
     exposed-modules:
+        Development.IDE.Core.Completions
+        Development.IDE.Core.CompletionsTypes
         Development.IDE.Core.FileStore
         Development.IDE.Core.OfInterest
         Development.IDE.Core.PositionMapping
@@ -123,6 +126,7 @@ library
         Development.IDE.GHC.Warnings
         Development.IDE.Import.FindImports
         Development.IDE.LSP.CodeAction
+        Development.IDE.LSP.Completions
         Development.IDE.LSP.HoverDefinition
         Development.IDE.LSP.Notifications
         Development.IDE.Spans.AtPoint
@@ -180,6 +184,7 @@ test-suite ghcide-tests
         ghcide:ghcide,
         ghcide:ghcide-test-preprocessor
     build-depends:
+        aeson,
         base,
         bytestring,
         containers,