Generate list of enum values in help text as lowercase

Since there is a parser option `CaseInsensitiveEnumValues` it would be also desirable to output help text for enum options in lowercase. Right now it outputs enum names as-is, most popular being PacalCase. This may be an option for `HelpText.AutoBuild`.

Start with the parser option CaseInsensitiveEnumValues and the HelpText.AutoBuild path mentioned in the issue, then trace how enum names are added to generated help text. Determine whether lowercase output should be controlled by an AutoBuild option, and verify that generated enum help values use the intended casing.

Written by the indexing model from the issue text.