Create flipper-server-client package

Summary:
FlipperServerClient is a useful abstraction for any JS-based client of headless Flipper. No need to bundle it with flipper-frontend-core, as the rest is not useful for external clients.
Currently, I am planning to add it to jest-e2e to send commands to Flipper

Reviewed By: lblasa

Differential Revision: D40765668

fbshipit-source-id: af48710bb15444ac1ecd649fe9a2ab252f3088f3

desktop/flipper-server-client/tsconfig.json

@@ -0,0 +1,13 @@
+{
+  "extends": "../tsconfig.base.json",
+  "compilerOptions": {
+    "outDir": "lib",
+    "rootDir": "src",
+    "lib": ["dom", "ES2019"]
+  },
+  "references": [
+    {
+      "path": "../flipper-common"
+    }
+  ]
+}