Add support for integers and tool configuration in schema handling

This update introduces support for `jsonschema.Integer` types and updates the logic to handle nested items in schemas. Added a new default error log for unknown types using `slog.Error`. Also, integrated tool configuration with a `FunctionCallingConfig` when `dontRequireTool` is false.

schema/type.go

@@ -1,12 +1,15 @@
 package schema
 
 import (
+	"github.com/openai/openai-go"
 	"reflect"
 
 	"github.com/sashabaranov/go-openai/jsonschema"
 )
 
 type Type interface {
+	FunctionParameters() openai.FunctionParameters
+
 	SchemaType() jsonschema.DataType
 	Definition() jsonschema.Definition