ui/console: rename public API to use consistent qemu_console_ prefix

Rename the display and graphic console public functions to follow a
consistent qemu_console_ (or qemu_graphic_console_) naming convention.

The previous API used a mix of prefixes: dpy_, graphic_hw_,
graphic_console_, console_has_, and update_displaychangelistener().
Unify them under a common qemu_console_ namespace for better
discoverability and consistency.

The main renames are:
- dpy_gfx_*() / dpy_text_*() / dpy_gl_*() → qemu_console_*()
- dpy_{get,set}_ui_info() → qemu_console_{get,set}_ui_info()
- graphic_hw_*() → qemu_console_hw_*()
- graphic_console_*() → qemu_graphic_console_*()
- console_has_gl() → qemu_console_has_gl()
- update_displaychangelistener() → qemu_console_listener_set_refresh()

No functional changes.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>