[form] Add support for dynamically created interactive forms

Add support for presenting a dynamic user interface as an interactive
form, alongside the existing support for presenting a dynamic user
interface as a menu.

An interactive form may be used to allow a user to input (or edit)
values for multiple settings on a single screen, as a user-friendly
alternative to prompting for setting values via the "read" command.

In the present implementation, all input fields must fit on a single
screen (with no scrolling), and the only supported widget type is an
editable text box.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/config/config.c

@@ -227,6 +227,9 @@ REQUIRE_OBJECT ( sanboot_cmd );
 #ifdef MENU_CMD
 REQUIRE_OBJECT ( dynui_cmd );
 #endif
+#ifdef FORM_CMD
+REQUIRE_OBJECT ( dynui_cmd );
+#endif
 #ifdef LOGIN_CMD
 REQUIRE_OBJECT ( login_cmd );
 #endif

src/config/general.h

@@ -145,6 +145,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 #define DHCP_CMD		/* DHCP management commands */
 #define SANBOOT_CMD		/* SAN boot commands */
 #define MENU_CMD		/* Menu commands */
+#define FORM_CMD		/* Form commands */
 #define LOGIN_CMD		/* Login command */
 #define SYNC_CMD		/* Sync command */
 #define SHELL_CMD		/* Shell command */