Add Parcel detector

[travishorn]

- Summary

The Netlify CLI does not currently detect the bundler Parcel. This pull request adds a detector to detect it.

- Test plan

Create the file src/index.html. At a minimum it should contain valid HTML.

Install parcel-bundler.

npm i -D parcel-bundler

Add a dev script in package.json.

"scripts": {
  "dev": "parcel src/index.html",
},

Run Netlify Dev.

netlify dev

Parcel bundles the project and serves a hot-reloading dev server on port 1234. Netlify Dev proxies it on port 8888.

PS C:\Users\thorn\Development\netlifytest> netlify dev

◈ Netlify Dev ◈
◈ Starting Netlify Dev with parcel
Waiting for localhost:1234.
◈ Lambda server is listening on 34567

> netlifytest@2.2.4 dev C:\Users\thorn\Development\netlifytest
> parcel src/index.html

Server running at http://localhost:1234 
√  Built in 673ms.
.
Connected!
Waiting for localhost:34567.
Connected!

   ┌─────────────────────────────────────────────────┐
   │                                                 │
   │   ◈ Server now ready on http://localhost:8888   │
   │                                                 │
   └─────────────────────────────────────────────────┘

- Description for the changelog

Added Parcel detector

- A picture of a cute animal (not mandatory but encouraged)
🐱

[RaeesBhatti]

Tested and seems good to merge. Thanks 👍🏽