Database Lab access using the `pgai` Ruby gem

WARNING: The pgai gem has not yet been updated to use the new database lab instances so you will only be able to access gitlab-production-main and gitlab-production-ci using this tool.

@mbobin created the pgai Ruby Gem that greatly simplifies access to a database clone, with support for:

Access to all database clones listed in the Postgres.ai instances page;
Multiple psql sessions on the same clone.

If you have AllFeaturesUser psql access, you can follow the steps below to configure the pgai Gem:

To get started, you need to gather some values from the Postgres.ai instances page:
1. Go to the instance that you want to configure and the on right side of the screen.
2. Under Connection, select Connect. The menu might be collapsed.
  
  A dialog with everything that's needed for configuration appears, using this format:
```
dblab init --url "http://127.0.0.1:1234" --token TOKEN --environment-id <environment-id>
```
```
ssh -NTML 1234:localhost:<environment-port> <postgresai-user>@<postgresai-proxy> -i ~/.ssh/id_rsa
```

Add the following snippet to your SSH configuration file at ~/.ssh/config, replacing the variable values:

Host pgai-proxy
  HostName <postgresai-proxy>
  User <postgresai-user>
  IdentityFile ~/.ssh/id_ed25519

Run the following command so you can accept the server key fingerprint:
```
ssh pgai-proxy
```

Run the following commands:

gem install pgai

# Grab an access token: https://console.postgres.ai/gitlab/tokens
# GITLAB_USER is your GitLab handle
pgai config --dbname=gitlabhq_dblab --prefix=$GITLAB_USER --proxy=pgai-proxy

# Grab the respective port values from https://console.postgres.ai/gitlab/instances
# for the instances you'll be using (in this case, for the `main` database instance)
pgai env add --alias main --id <environment-id> --port <environment-port>

Once this one-time configuration is done, you can use pgai connect to connect to a particular database. For instance, to connect to the main database:
```
pgai connect main
```
Once done with the clone, you can destroy it:
```
pgai destroy main
```

Database Lab access using the pgai Ruby gem

Database Lab access using the `pgai` Ruby gem