Improve the banner output of `dotnet watch` to make it clearer when things are disabled, how to diagnose issues, etc.

`dotnet watch` has some behaviors today that can be hard to discover but impact the user experience. These things could be called out in a more informative "banner" that's emitted to the console when the tool is run. The following things seem worth considering including details about:
- How to disable Hot Reload (cmd line arg, `launchSettings.json` property, etc.), or link to a doc
- The reason why Hot Reload or aspects of it are disabled on launch, e.g. when Razor runtime compilation is present in the project
- How to enable displaying of more details about rude edits (i.e. `--verbose`)