Feature Request - Ability to set WPF context menu's style

[chucker]

Describe the solution you'd like
I moved from IContextMenuHandler to CefSharp.Wpf.Handler.ContextMenuHandler in order to avoid #1882.

As a result, the context menu now has the default WPF styling, which doesn't really fit Chrome or modern Windows.

I would like to be able to set the context menu's Style property; however, the context menu is instantiated ad-hoc, so this doesn't seem possible. I.e., I would like

• either a property ContextMenuStyle on CefSharp.Wpf.ChromiumWebBrowser to set the style beforehand, then if set, have CefSharp.Wpf.Handler.ContextMenuHandler apply it
• or an event ContextMenuCreated in CefSharp.Wpf.Handler.ContextMenuHandler which I can listen to

Describe alternatives you've considered

• implementing IContextMenuHandler myself (or inheriting from CefSharp.Wpf.Handler.ContextMenuHandler. However, that seems like a lot of error-prone work.
• using CefSharp.Wpf.Handler.ContextMenuHandler but overriding RunContextMenu to grab the created ContextMenu. This doesn't (seem to) work reliably due to timing issues.

Checklist:

• I have reviewed the CEF API and have confirmed the feature I'm requesting is possible.
  - [ ] The Feature I'm requesting is an improvement to Async Javascript Binding (No new feature are being added to the Sync Javascript binding)
  - [ ] An open PR exists on the CEF Pull Requests and I'd like to propose this feature is added to CefSharp when/if it's merged.