Manage half-stack config files by collecting them in one place

## Motivation  

- When user install [http://backend.ai](http://backend.ai) with the current install-dev.sh or tui installer, installer will copy the configuration files that were in the configs folder to the [http://backend.ai](http://backend.ai) root path and use them.
With the recent addition of components, there are a lot of configuration files, and we want to put them in one place to make it easier for you to manage them.

## Objective  

- Make sure to specify an appropriate path for the configuration files and make it clear that it is separate from the existing configs folder.

JIRA Issue: BA-737