new_registration: Move human verification from popup to inline style.

Placed text just below the "Create organization" button.
Used styling to match "Learn how to import..." above.
Hidden the checkbox after the verification is done.
The verification text is hidden after 2s with a fadeout after 1s delay.

Fixes #36086

zerver/forms.py

@@ -358,7 +358,6 @@ class AltchaWidget(forms.TextInput):
                 '  challengeurl="/json/antispam_challenge"'
                 "  hidelogo"
                 "  hidefooter"
-                '  floating="bottom"'
                 "  refetchonexpire"
                 '  style="{}"'
                 '  strings="{}"'