Allow the accessible markdownEditor prompt to be blank when the blank
comes from the result of an interactive session with an editor, even when
blankAllowed is false.
This behavior aligns the accessible prompter with the behavior of the
current standard prompter.
This commit refactors the color format around table headers to ensure the GitHub CLI uses thematically appropriate colors based on dark background, light background, or no color at all.
In order to do so, `ColorScheme` needs information from the terminal about the background appearance (dark, light, none) to determine appropriate muted color.
During discussion in cli/cli#9934, we can to the conclusion that the logic around checking for core GitHub CLI updates would diverge from GitHub CLI
extension updates over time. To that end, this commit splits that logic into a separate function with a new environment variable.
This commit expands the in-line docs around updaterEnabled package variable used to affect release checking.
Along with clarifying specific details discovered when talking with @williammartin, I'm also removing a useless local variable.
After merging in upstream changes regarding local extensions, this commit addresses remaining PR feedback while also bringing the newly merged tests into alignment with other changes.
- this was something I did in the original implementation of this improved extension update notification logic
- discovering other parts of the extension manager code that were working with non-prefixed extension names motivated a different approach
- the extension manager code that requires the extension be prefixed has been enhanced to use the centralized ensurePrefixed() logic, making the need for this on the extension unnecessary
