1.5.1-1.21.7

Optimized the parsing of JSON text.
When typing special texts in the sign, if the content is invalid (for example, -json with an invalid JSON text), the text field will be now displayed red.
Fixed the issue that the side texture of road blocks with straight line and two bevel angle lines will disappear on some occasions.
Fixed the issue that in the sign edit interface, the underline button changes the italic of text by mistake.