Update pxt.json include new files

Includes new files and recently renamed files:
- Renames:
    1. `switch.ts` : `switchblock.ts`
    2. `case.ts` : `caseblock.ts`
- New:
    1. `classes/switchcontext.ts`
    2. `classes/switchmanager.ts`

Author: seriussoft

pxt.json

@@ -4,8 +4,10 @@
     , "description": "Adds a switch-case block for MakeCode Arcade"
     , "files": [
         "main.ts"
-        , "switch.ts"
-        , "case.ts"
+        , "switchblock.ts"
+        , "caseblock.ts"
+        , "classes/switchcontext.ts"
+        , "classes/switchmanager.ts"
     ],
     " public": true
     , "supportedTargets": [
@@ -15,4 +17,4 @@
         "device": "*"
     }
     , "testDependencies": {}
-}
+}