[now-build-utils] Fix now dev to use system node (#3509)

This PR will use the system installed version of Node.js and avoid printing a warning or error if a discontinued version is selected.

This optimization was already in `@now/node` but for some reason it was never add to `@now/next`.

The reason why its relevant today is because the warnings turned into errors due to Node 8 deprecation and we don't have the "Project" in `now dev` so we don't know which version of node to select.

So instead of determining the version, `now dev` will always use `node` in the PATH and avoid printing warnings or errors. This also results in less FS reads since we no longer need to read package.json.

test/lib/run-build-lambda.js

@@ -1,5 +1,8 @@
-const getWritableDirectory = require('../../packages/now-build-utils/fs/get-writable-directory.js');
-const glob = require('../../packages/now-build-utils/fs/glob.js');
+const {
+  getLatestNodeVersion,
+  glob,
+  getWriteableDirectory,
+} = require('@now/build-utils');
 
 function runAnalyze(wrapper, context) {
   if (wrapper.analyze) {
@@ -16,6 +19,11 @@ async function runBuildLambda(inputPath) {
   const nowJson = require(nowJsonRef.fsPath);
   expect(nowJson.builds.length).toBe(1);
   const build = nowJson.builds[0];
+  if (!build.config || !build.config.nodeVersion) {
+    // Mimic api-deployments when a new project is created
+    const nodeVersion = getLatestNodeVersion().range;
+    build.config = { ...build.config, nodeVersion };
+  }
   expect(build.src.includes('*')).toBeFalsy();
   const entrypoint = build.src.replace(/^\//, ''); // strip leftmost slash
   expect(inputFiles[entrypoint]).toBeDefined();
@@ -26,15 +34,15 @@ async function runBuildLambda(inputPath) {
   const analyzeResult = runAnalyze(wrapper, {
     files: inputFiles,
     entrypoint,
-    config: build.config
+    config: build.config,
   });
 
-  const workPath = await getWritableDirectory();
+  const workPath = await getWriteableDirectory();
   const buildResult = await wrapper.build({
     files: inputFiles,
     entrypoint,
     config: build.config,
-    workPath
+    workPath,
   });
   const { output } = buildResult;
 
@@ -43,7 +51,7 @@ async function runBuildLambda(inputPath) {
     buildResult.output = Object.keys(output).reduce(
       (result, path) => ({
         ...result,
-        [path.replace(/\\/g, '/')]: output[path]
+        [path.replace(/\\/g, '/')]: output[path],
       }),
       {}
     );
@@ -52,7 +60,7 @@ async function runBuildLambda(inputPath) {
   return {
     analyzeResult,
     buildResult,
-    workPath
+    workPath,
   };
 }