Refactor deprecated BrowserView API example

[aadcg]

Note that under "Show Me" -> "Electron APIs" -> "BrowserView", the example displayed still uses the deprecated API.

[Santhoshmani1]

The latest documentation suggests to use the WebContentsView Class to display the web contents.

The BrowserView class is deprecated, and replaced by the new WebContentsView class.
https://www.electronjs.org/docs/latest/api/browser-view

We should remove the browserview/main.js and should add a new file for the WebContentsView Class.

Here is the code provided under the WebContentsView class that we can add under the show-me examples.

const { BaseWindow, WebContentsView } = require('electron')
const win = new BaseWindow({ width: 800, height: 400 })

const view1 = new WebContentsView()
win.contentView.addChildView(view1)
view1.webContents.loadURL('https://electronjs.org')
view1.setBounds({ x: 0, y: 0, width: 400, height: 400 })

const view2 = new WebContentsView()
win.contentView.addChildView(view2)
view2.webContents.loadURL('https://github.com/electron/electron')
view2.setBounds({ x: 400, y: 0, width: 400, height: 400 })

[Santhoshmani1]

Should we remove the BrowserView Class example from the Show-me section or should we leave it as it is.