Set NODE_PATH when forking TS server

The ensures that we can resolve require('typescript') inside of plugins correctly

extensions/postinstall.js

@@ -7,7 +7,7 @@
 
 const fs = require('fs');
 const path = require('path');
-const toDelete = new Set(['tsc.js', 'tsserverlibrary.js', 'typescriptServices.js']);
+const toDelete = new Set(['tsc.js', 'typescriptServices.js']);
 
 const root = path.join(__dirname, 'node_modules', 'typescript', 'lib');
 for (let name of fs.readdirSync(root)) {

extensions/typescript/src/utils/electron.ts

@@ -94,6 +94,7 @@ export function fork(
 
 
 	const newEnv = generatePatchedEnv(process.env, stdInPipeName, stdOutPipeName, stdErrPipeName);
+	newEnv['NODE_PATH'] = path.join(modulePath, '..', '..', '..');
 	let childProcess: cp.ChildProcess;
 
 	// Begin listening to stderr pipe