### Godot version

v4.1.dev.custom_build.a7276f1ce

### System information

Win10, AMD 2600, GeForce GTX 1060, Vulkan API 1.3.205

### Issue description

I can't get correct color data from an array of source_color type.
The color data is saved as **Color** in the file:
`shader_parameter/palette = [Color (1, 0, 0, 1), Color (0, 1, 0, 1), Color (0, 0, 1, 1)]`
Shouldn't it be saved as PackedColorArray?


### Steps to reproduce

1.Declare an array of source_color type.
2.Set colors.

### Minimal reproduction project

[shadertest.zip](https://github.com/godotengine/godot/files/11246504/shadertest.zip)

switch (p_node->type) {
		case Node::NODE_TYPE_OPERATOR: {
			const OperatorNode *op_node = static_cast<const OperatorNode *>(p_node);
			for (int i = int(op_node->op == OP_CALL); i < op_node->arguments.size(); i++) {
				if (!_check_node_constness(op_node->arguments[i])) {
					return false;
				}
			}
		} break;
		case Node::NODE_TYPE_CONSTANT:
			break;
		case Node::NODE_TYPE_VARIABLE: {
			const VariableNode *var_node = static_cast<const VariableNode *>(p_node);
			if (!var_node->is_const) {
				return false;
			}
		} break;
		case Node::NODE_TYPE_ARRAY: {
			const ArrayNode *arr_node = static_cast<const ArrayNode *>(p_node);
			if (!arr_node->is_const) {
				return false;
			}
		} break;
		default:
			return false;
	}
	return true;
}
bool ShaderLanguage::_validate_assign(Node *p_node, const FunctionInfo &p_function_info, String *r_message) {