fix(sdk build, package.json): added a copy-files script which is OS independent

Previously we were using cp command to copy services.proto file from proto folder to dist folder but
cp command doesnt work for windows and hence the build fails in windows. I added "copy-files" script
which uses copyfiles npm module to copy proto file and is OS independent.

fix #51

Signed-off-by: Hermione Dadheech <hermionedadheech@gmail.com>

Author: Hermione2408

package.json

@@ -6,9 +6,10 @@
     "dist"
   ],
   "scripts": {
-    "build": "tsc && cp ./proto/services.proto ./dist/proto/",
+    "build": "tsc && yarn copy-files",
     "prepare": "npm run build",
-    "commit": "cz"
+    "commit": "cz",
+    "copy-files":"copyfiles -u 1 ./proto/services.proto ./dist/proto/"
   },
   "repository": "git@github.com:keploy/typescript-sdk.git",
   "author": "Rajat Sharma <lunasunkaiser@gmail.com>",
@@ -49,6 +50,7 @@
     "import-in-the-middle": "^1.3.4",
     "merge-descriptors": "^1.0.1",
     "node-fetch": "^2.6.7",
-    "require-in-the-middle": "^5.1.0"
+    "require-in-the-middle": "^5.1.0",
+    "copyfiles": "^2.4.1"
   }
 }