Add cmdlime::Format::GNUWindows

[kamchatka-volcano]

This is the GNU format with the ability to register alternative names starting with a forward slash.

All names are in kebab-case.
Parameters and flags prefix: --
Short names are supported. Short names prefix: -
Parameters usage: --parameter value, --parameter=value, -p value or -pvalue. /parameter:value and /parameter value are also supported, they have to be enabled with << WithSlashForm{} modifier or <<WithShortNameSlashForm to add /p:value or /p value, or << SlashName{"custom-name"} and << SlashShortName{"c"} to override an automatic name generation.
Flags usage: --flag, -f. /flag or /f are also supported. They have to be enabled with << WithSlashForm{} or <<WithShortNameSlashForm modifiers, or << SlashName{"custom-name"} and << SlashShortName{"c"} to override an automatic name generation.
Flags in short form (except those that start with a slash) can be "glued" together: -abc or with one parameter: -fp value.
Default help flag: -h, --help, -?, or /?.