Before, when adding parsed information to the IRemainingArguments.Parsed,
we used the name of the parsed option ('foo') instead of it's
representation ('--foo'). This commit fixes that.
Commit d3f4f5f208 introduced automatic conversion to FileInfo and DirectoryInfo but failed to properly handle the conversion if the value comes from the [DefaultValue] attribute.
Using both `var (converter, stringConstructor) = GetConverter(...)` and `var (converter, _) = GetConverter(...)` should have been a red flag!
Allow custom help providers
* Version option will show in help even with a default command
* Reserve `-v` and `--version` as special Spectre.Console command line arguments (nb. breaking change for Spectre.Console users who have a default command with a settings class that uses either of these switches).
* Help writer correctly determines if trailing commands exist and whether to display them as optional or mandatory in the usage statement.
* Ability to control the number of indirect commands to display in the help text when the command itself doesn't have any examples of its own. Defaults to 5 (for backward compatibility) but can be set to any integer or zero to disable completely.
* Significant increase in unit test coverage for the help writer.
* Minor grammatical improvements to website documentation.
* Support negative numbers as command option values
* Support command line options before arguments
* POSIX-compliant handling of quotes (double and single, terminated and unterminated), whitespace, hyphens, and special characters (e.g. emojis)
