Add batteryState to robot

[Eddasol]

PR to make the charging state from the robot available on the robot object. Corresponding frontend change isn't implemented yet to prevent conflict with rewriting/removal of localization.

Related to: equinor/isar#675

Ready for review checklist:

• A self-review has been performed
• All commits run individually
• Temporary changes have been removed, like console.log, TODO, etc.
• The PR has been tested locally
• A test have been written
  • This change doesn't need a new test
• Relevant issues are linked
• Remaining work is documented in issues
  • There is no remaining work from this PR that require new issues
• The changes does not introduce dead code as unused imports, functions etc.

[github-actions]

🔔 Changes in database folder detected 🔔
Do these changes require adding new migrations? 🤔 In that case follow these steps.
If you are uncertain, ask a database admin on the team 😄

[github-actions]

🔔 Migrations changes detected 🔔
📣 Remember to comment "/UpdateDatabase" after review approval for migrations to take effect!