- added support for `accessible_colors` configuration setting in `gh config` commandset
- updated default configuration file to contain `accessible_colors: disabled`
- add `GH_ACCESSIBLE_COLORS` env var to `gh environment`
- generated mocks via `go generate ./...` including previously missed prompter changes
This commit implements the actual changes around configuration setting / environment variable logic for displaying labels using their RGB hex color code in terminals with truecolor support.
One of the subtler changes in this commit is renaming generic ColorScheme.HexToRGB logic to render truecolor to ColorScheme.Label as this feature was being used exclusively for labels. This is due to confusion about introducing the new `color_labels` config on top of generic coloring logic.
