feat: add sites rename command

[vigneshrajsb]

Description

• Adds lfc sites rename <id> <name> to change a site's display name. The site ID and URL stay the same.
• Adds the generated RenameSiteBody type and updates the README and help text.

Verifying Changes

• pnpm validate and pnpm test pass.

Notes

• Needs the API change in GoodRxOSS/lifecycle. Generated types were added for this endpoint only; the rest of the committed types are already out of date with the API.