DRAFT: lib/battery: rename plugin/battery

[gaelicWizard]

Description

This plugin only provides utility functions, so it has zero cost to just being enabled. This allows us to eliminate assumptions from lib/theme and several themes.

Motivation and Context

The plugin changes not one thing by being enabled, except providing some utility functions used by a couple of themes. Those themes, and even the themes/base.theme.bash file, have multiple tests to check whether the plugin is loaded or not. Moving the utility functions under lib allows them to be used by the themes without special handling. If the user enables the theme to show the battery, then it should just work without alsö having to enable a plugin.

How Has This Been Tested?

Types of changes

• Enhancement (non-breaking change which makes things better)

Checklist:

• My code follows the code style of this project.
• If my change requires a change to the documentation, I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• If I have added a new file, I also added it to clean_files.txt and formatted it using lint_clean_files.sh.
• I have added tests to cover my changes, and all the new and existing tests pass.

[seefood]

In general this looks good. do we close the deal? needs a fresh merge from master first.