Replace existing webview with same title instead of open a new one #214

Thanks for the great extension!

I'm using View() a lot to inspect my tables. The current behaviour of this extension is to open a new webview every time View() is called.

However, I would like to be able to configure this to behave the same way as in RStudio:
If View() is called, and there is an existing tab with the same title (i.e. View's title= argument), that tab is updated instead of opening a new one.