Add initial implementation of Flagsmith server provider

Author: matthewelwell

libs/providers/flagsmith/package-lock.json

@@ -0,0 +1,13 @@
+{
+  "name": "@openfeature/flagsmith-provider",
+  "version": "0.1.0",
+  "scripts": {
+    "publish-if-not-exists": "cp $NPM_CONFIG_USERCONFIG .npmrc && if [ \"$(npm show $npm_package_name@$npm_package_version version)\" = \"$(npm run current-version -s)\" ]; then echo 'already published, skipping'; else npm publish --access public; fi",
+    "current-version": "echo $npm_package_version"
+  },
+  "license": "Apache-2.0",
+  "dependencies": {
+    "@openfeature/server-sdk": "^1.19.0",
+    "flagsmith-nodejs": "^6.1.0"
+  }
+}

libs/providers/flagsmith/package.json

@@ -0,0 +1 @@
+export * from './lib/flagsmith-client-provider';

libs/providers/flagsmith/src/index.js

@@ -0,0 +1,10 @@
+import { ErrorCode } from '@openfeature/core';
+
+class FlagsmithProviderError extends Error {
+  constructor(message: string, public code: ErrorCode) {
+    super(message);
+    this.name = "FlagsmithProviderError";
+  }
+}
+
+export { FlagsmithProviderError };