Add Devcontainer Support

[aroop]

Description

This PR adds support for Devcontainers to streamline the development environment setup process using Visual Studio Code. With this update, developers can easily configure and launch the project within a containerized environment, ensuring consistency across different development setups.

Changes

• Added .devcontainer directory with necessary configuration files.
• Updated database.yml to use the ENV variables if they are set
• Created new bin/setup-devcontainer which does not install Postgres and Redis as they are available as services

Instructions to Test

1. Clone the Repository:

git clone git@github.com:bullet-train-co/bullet_train.git your_new_project_name

2. Navigate to the Project Directory:

cd your_new_project_name

3. Run Initial Configuration:

./bin/configure

Note: This step needs to be run locally once at the time of project setup.

Open in VS Code:

• Open the project in Visual Studio Code.
• Select "Reopen in Container" to complete the setup.

This setup ensures a consistent development environment and simplifies new project setup

[aroop]

This PR helps with issue like

#1608
#1606

[jagthedrummer]

Hey, @aroop, thanks for the PR! I don't use VSC so I'm not really equipped to give this a full review. I'm going to ping some of the other folks on the core team and see if one of them can give it a run.

[gazayas]

Hey @aroop, this looks great! I like the idea of running the app in a docker container this way. A couple things:

1. The initial steps you laid out look like this:
   1. Clone the Repository
   2. Navigate to the Project Directory
   3. Run Initial Configuration: ./bin/configure
      If we're trying to solve problems bin/setup doesn't tell me how to fix NodeJS version or yarn issue #1608, I'm curious if we should prompt the developer to open VS Code first and run ./bin/configure from the terminal there. I saw your note that says "This step needs to be run locally once at the time of project setup." concerning ./bin/configure. What's the rationale for running ./bin/configure first as opposed to checking node/Ruby versions within the container itself? I'm not saying the order is incorrect, I'm just trying to understand the flow for starting/using the docker container.
2. This is probably just a lack of understanding on my part of docker, but I'm having trouble running the container itself. Docker seems to be working properly on my side:

> docker --version
Docker version 27.1.2, build d01f264
> whoami
gazayas
> cat /etc/group | grep docker
docker:x:998:gazayas

However, when I open VS Code and try to reopen it with the container, I get a permission denied error:

I also tried to add the user to devcontainer.json:

"remoteUser": "gazayas",
"containerUser": "gazayas"

No luck here either. I also tried changing the VS Code profile from Default to gazayas, to no avail. Anything I'm missing?

Either way, I do like the idea and think adding it to the project would be really helpful!

[JeremiahChurch]

I'd propose adding an env variable to improve the corepack prompt on the install process

environment:
      COREPACK_ENABLE_DOWNLOAD_PROMPT: 0 # prevent yarn install y/n prompt