feat: allow specifying proxy when creating project

close #1009

Author: yyx990803

Diff for: packages/@vue/cli/bin/vue.js

@@ -44,6 +44,7 @@ program
   .option('-g, --git [message]', 'Force / skip git intialization, optionally specify initial commit message')
   .option('-f, --force', 'Overwrite target directory if it exists')
   .option('-c, --clone', 'Use git clone when fetching remote preset')
+  .option('-x, --proxy', 'Use specified proxy when creating project')
   .action((name, cmd) => {
     require('../lib/create')(name, cleanArgs(cmd))
   })

Diff for: packages/@vue/cli/lib/create.js

@@ -9,10 +9,14 @@ const { error, stopSpinner } = require('@vue/cli-shared-utils')
 const validateProjectName = require('validate-npm-package-name')
 
 async function create (projectName, options) {
+  if (options.proxy) {
+    process.env.HTTP_PROXY = options.proxy
+  }
+
   const inCurrent = projectName === '.'
   const name = inCurrent ? path.relative('../', process.cwd()) : projectName
   const targetDir = path.resolve(projectName || '.')
-  
+
   const result = validateProjectName(name)
   if (!result.validForNewPackages) {
     console.error(chalk.red(`Invalid project name: "${projectName}"`))