docs: document db:create and db:drop commands

[batosai]

🔗 Linked PR

adonisjs/lucid#1183

❓ Type of change

• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

Follow-up documentation for adonisjs/lucid#1183, which adds the db:create and db:drop commands.

This PR updates the commands reference (content/docs/guides/commands.md):

• New db:create section: creating the database of a connection, idempotent behavior (no-op when the database already exists), how Lucid connects to the maintenance database of the dialect since the target database may not exist, file creation on SQLite/libSQL, the --connection flag, plus a note about required privileges (global CREATE on MySQL) and OracleDB not being supported.
• New db:drop section: difference with db:wipe (drops the database itself, not the tables inside it), file removal on SQLite/libSQL, the production confirmation prompt, and the --connection / --force flags.
• Updated the intro sentence so the db:* family covers the database lifecycle, not only seeding and clearing data.

Should be merged once adonisjs/lucid#1183 lands.

• I have linked an issue or discussion.
• I have updated the documentation accordingly.