feat: add options to cover project files by transforming

[konpeki622]

closes #97 .

Usage: webpack-to-vite -d projectPath -c or webpack-to-vite -d projectPath --cover to cover raw files. By default it create a new directory named projectName-toVite and transform files in the new directory.

Usage: webpack-to-vite [options] [root]

Options:
  -v, --version            display version number
  -d --rootDir <path>      the directory of project to be converted
  -t --projectType <type>  the type of the project, use vue-cli or webpack (default: vue-cli)
  -e --entry <type>        entrance of the entire build process, webpack or vite will start from those entry files to       
                           build, if no entry file is specified, src/main.ts or src/main.js will be used as default
  -c --cover               transformed project files will cover the raw files
  -h, --help               display help for command

[konpeki622]

When executing webpack-to-vite without option -c:

1. copy files to outputDir expect node_modules directory
2. generate vue.temp.config.js in outputDir and delete it when transformation completed
3. transform files in sourceDir and write the results to outputDir