VisualShader varyings names can break the shader

[Grandro]

Tested versions

• 4.2.2
• 4.3-dev6

System information

Windows 10

Issue description

You can name a varying in a visual shader nearly however you want and the generated code just copies the name over 1:1, so you can (accidentally) choose protected keywords. E.g.:
varying, float, shader_type , ...
which breaks the shader.

A possible solution would be to always add some sort of suffix/prefix or to prevent the user from choosing such a name:
varying => Varying_varying
float => Varying_float

Steps to reproduce

1. Create a new project
2. Create a VisualShader, apply it to a Material and the Material to a Sprite
3. Create any varying with a reserved keyword name

Minimal reproduction project (MRP)

VaryingNaming.zip