split BrowserView.cs into separate classes

Runtime/BrowserView.cs

Runtime/ChromeDevtools.meta

Runtime/ChromeDevtools/Browser.cs

Runtime/ChromeDevtools/Browser.cs.meta

Runtime/ChromeDevtools/BrowserTab.cs

Runtime/ChromeDevtools/BrowserTab.cs.meta

Runtime/ChromeDevtools/PageTargetInfo.cs

Runtime/ChromeDevtools/PageTargetInfo.cs.meta

Runtime/ChromeDevtools/Protocol.meta

Runtime/ChromeDevtools/Protocol/CaptureScreenshot.cs

Runtime/ChromeDevtools/Protocol/CaptureScreenshot.cs.meta

Runtime/ChromeDevtools/Protocol/DevtoolsCommand.cs

Runtime/ChromeDevtools/Protocol/DevtoolsCommand.cs.meta

Runtime/ChromeDevtools/Protocol/Target.meta

Runtime/ChromeDevtools/Protocol/Target/CloseTarget.cs

Runtime/ChromeDevtools/Protocol/Target/CloseTarget.cs.meta

Runtime/ChromeDevtools/Protocol/Types.meta

Runtime/ChromeDevtools/Protocol/Types/Viewport.cs

Runtime/ChromeDevtools/Protocol/Types/Viewport.cs.meta