Validate call params for gd_self virtual methods.

[Yarwin]

closes: #1374

Before this PR, following code:

#[derive(GodotClass)]
#[class(init, base = Node)]
struct MyClass {
    base: Base<Node>,
}

#[godot_api]
impl INode for MyClass {
    #[func(gd_self)]
    fn physics_process(_this: Gd<Self>) {

    }

    #[func(gd_self)]
    fn process(_this: Gd<Self>, _delta: i32) {}
}

did compile without issues, now it throws following errors:

error[E0308]: mismatched types
  --> src/lib.rs:19:5
   |
16 | #[godot_api]
   | ------------ expected due to this
...
19 |     fn physics_process(_this: Gd<Self>) {
   |     ^^ expected `(f64,)`, found `()`
   |
   = note:  expected tuple `(f64,)`
           found unit type `()`

error[E0308]: mismatched types
  --> src/lib.rs:24:5
   |
16 | #[godot_api]
   | ------------ expected due to this
...
24 |     fn process(_this: Gd<Self>, _delta: i32) {}
   |     ^^ expected `(f64,)`, found `(i32,)`
   |
   = note: expected tuple `(f64,)`
              found tuple `(i32,)`

error[E0308]: mismatched types
  --> src/lib.rs:16:1
   |
16 |   #[godot_api]
   |   ^^^^^^^^^^^^ expected `i32`, found `f64`
17 |   impl INode for MyClass {
   |  ________________-
18 | |     #[func(gd_self)]
19 | |     fn physics_process(_this: Gd<Self>) {
...  |
23 | |     #[func(gd_self)]
24 | |     fn process(_this: Gd<Self>, _delta: i32) {}
   | |______________- arguments to this function are incorrect
   |
note: associated function defined here
  --> src/lib.rs:24:8
   |
24 |     fn process(_this: Gd<Self>, _delta: i32) {}
   |        ^^^^^^^                  -----------
   = note: this error originates in the attribute macro `godot_api` (in Nightly builds, run with -Z macro-backtrace for more info)

[GodotRust]

API docs are being generated and will be shortly available at: https://godot-rust.github.io/docs/gdext/pr-1382

[Bromeon]

Thanks a lot!

[Bromeon]

Suggested change

	fn make_tuple_sig_annotation(trait_base_class: &Ident, method_name: &Ident) -> TokenStream {
	fn make_sig_tuple_annotation(trait_base_class: &Ident, method_name: &Ident) -> TokenStream {

To be consistent with variable name.