✨ Add support for not needing ... as default value in required Query(), Path(), Header(), etc. (#4906)

* ✨ Do not require default value in Query(), Path(), Header(), etc

* 📝 Update source examples for docs with default and required values

* ✅ Update tests with new default values and not required Ellipsis

* 📝 Update docs for Query params and update info about default value, required, Ellipsis

docs_src/schema_extra_example/tutorial002.py

@@ -7,10 +7,10 @@ app = FastAPI()
 
 
 class Item(BaseModel):
-    name: str = Field(..., example="Foo")
-    description: Optional[str] = Field(None, example="A very nice Item")
-    price: float = Field(..., example=35.4)
-    tax: Optional[float] = Field(None, example=3.2)
+    name: str = Field(example="Foo")
+    description: Optional[str] = Field(default=None, example="A very nice Item")
+    price: float = Field(example=35.4)
+    tax: Optional[float] = Field(default=None, example=3.2)
 
 
 @app.put("/items/{item_id}")