[esphome] add chart

[hall]

Special notes for your reviewer:

This is mostly just a copy of the home-assistant chart with the extra containers and prometheus service monitor removed. I've also added it as a dependency of the home-assistant chart and enabled sharing the secrets.yaml file between the apps.

Checklist

[Place an '[x]' (no spaces) in all applicable fields. Please remove unrelated fields.]

• [x] Chart Version bumped
• [x] Variables are documented in the README.md
• [x] Title of the PR starts with chart name (e.g. [radarr])

[hall]

Tests are failing because the esphome chart doesn't exist in the repo. I'll remove the home-assistant chart changes and submit those in a separate PR.