localPublish plugin should prefer user-provided runtime

[benbrown]

Is your feature request related to a problem? Please describe.

The current localPublish plugin manages an "internal" copy of the bot project for testing purposes - it copies the declarative assets into a folder, and provides a copy of the runtime code.

This makes it hard and very confusing to make customizations to the runtime code or schema, as these files do not exist in the expected location.

If a user has customized or otherwise created a bot project on their own, Composer should attempt to use this copy of the code rather than providing its own.

Describe the solution you'd like

Update the localPublish plugin so it will use an existing bot project on disk if a copy of the runtime code is present. That is, it will run the project out of the user specified folder rather than copy it to an internal location.

See #2470 for info on how the custom runtime setting is controlled.

1. When localPublish.publish is called on a bot project, it will FIRST check the bot's settings for the custom runtime settings.
2. If custom runtime is not enabled, continue with current functionality of creating a "temporary" version of the project to run
3. If custom runtime is enabled, use the user-specified start command in the user-specified folder

[benbrown]

this is in progress!

[cwhitten]

#2572 (comment)