Enable setting locale per open bot/tab

[dmvtech]

When testing multiple bots at the same time that use different locales, it is somewhat cumbersome to do. First, you must open a bot in Emulator with first (default) locale, then open a second instance of Emulator, go into settings and change the locale, then open the bot.

Describe the solution you'd like
I would like to be able to set locale per opened bot. Ideally, on the Open Bot dialog. This would keep from having to open another instance of Emulator (which could be still be done if user preferred), instead just having a separate tab with different locale.

Additionally, having some more obvious indicator of what locale is actually being used currently (per opened bot) may help avoid issues such as this: microsoft/botbuilder-dotnet#5579
[enhancement]

[dmvtech]

We should also allow launching Emulator from Composer to apply the locale currently running/selected (or every locale?) in Composer (from the Emulator protocol).