Plutus core/fix cabal project file (#383)

* Remove redundant library dependencies identified by weeder

* Fix cabal.project file

* Add +development to plutus-playground-lib

cabal.project

@@ -6,8 +6,8 @@ packages: language-plutus-core
           plutus-tx-plugin
           plutus-use-cases
           plutus-ir
-          plutus-playground-server
-          plutus-playground-lib
+          plutus-playground/plutus-playground-server
+          plutus-playground/plutus-playground-lib
 optimization: 2
 constraints: language-plutus-core +development
            , wallet-api +development
@@ -16,6 +16,7 @@ constraints: language-plutus-core +development
            , plutus-core-interpreter +development
            , plutus-ir +development
            , plutus-playground-server +development
+           , plutus-playground-lib +development
 tests: true
 benchmarks: true
 documentation: true