Added icons to entities and changed device type to "battery" for batt…

[derolli1976]

Description

Added default icons for sensor entities and changed device type to "battery" for solar battery entities, so icon can reflect soc.
Icon map is maintained in const.py

Motivation and Context

Usability improvements and optics.

How Has This Been Tested?

Manual testing of icons.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.