feature: Make generate function assist generate a function as a constructor if the generated function has the name "new" and is an asscociated function.
close#17050
This PR makes `generate function assist` generate a function as a constructor if the generated function has the name "new" and is an asscociated function.
If the asscociate type is a record struct, it generates the constructor like this.
```rust
impl Foo {
fn new() -> Self {
Self { field_1: todo!(), field_2: todo!() }
}
}
```
If the asscociate type is a tuple struct, it generates the constructor like this.
```rust
impl Foo {
fn new() -> Self {
Self(todo!(), todo!())
}
}
```
If the asscociate type is a unit struct, it generates the constructor like this.
```rust
impl Foo {
fn new() -> Self {
Self
}
}
```
If the asscociate type is another adt, it generates the constructor like this.
```rust
impl Foo {
fn new() -> Self {
todo!()
}
}
```
84ef3cfa91