DEV: Run db:create in Docker dev container (#29295)

When attempting to [set up the Docker development environment](https://meta.discourse.org/t/install-discourse-for-development-using-docker/102009), I was seeing the following error when running `d/boot_dev --init`:

```
ActiveRecord::NoDatabaseError: We could not find your database: discourse_development. Available database configurations can be found in config/database.yml. (ActiveRecord::NoDatabaseError)
```

Running `db:create` before the `db:migrate` fixed this issue for me. It appears to be safe to run `db:create` even if the database already exists, running `d/rake db:create` locally shows an info message at the database already exists, but doesn't exit with an error.

bin/docker/boot_dev

@@ -122,6 +122,7 @@ echo "pnpm install..."
 
 if [ "${initialize}" = "initialize" ]; then
     echo "Migrating database..."
+    "${SCRIPTPATH}/rake" db:create
     "${SCRIPTPATH}/rake" db:migrate
     RAILS_ENV=test "${SCRIPTPATH}/rake" db:migrate