Async trait methods for no_std

Features like async-trait, avoid using Box and dyn.

This crate is ready for #![no_std] when PR69033 merged.

Thanks to crate async-trait, some code from these.

WARNING: This crate use some unstable even incomplete feature. You will get some warning from compiler.

Features

• [X] Self
  • [X] Self by reference.
  • [X] Self by value.
  • [X] Self by mut reference.
  • [X] no Self.
  • [X] any type of Self.
• [X] Any number of arguments, any return value.
  • [X] Arguments.
  • [X] As value.
  • [X] As reference without lifetime.
  • [X] Return value expect reference (return reference at Lifetime return).
• [X] Lifetime parameters.
  • [X] Lifetime arguments.
  • [ ] Lifetime return.
• [X] Associated types support.
• [X] Having async and non-async functions in the same trait.

Incomplete Feature

These feature all require generic_associated_types support type arguments.

Following issue: #44265

• [ ] support default async fn implementations in trait (Wait feature generic_associated_types support type arguments).
• [ ] Generic type parameters.
  • [ ] Generic arguments (Wait for feature generic_associated_types support type arguments).
  • [ ] Generic return (Wait for feature generic_associated_types support type arguments).
  • [ ] impl trait in arguments (Wait for feature generic_associated_types support type arguments).

Usage

Please enable feature type_alias_impl_trait and generic_associated_types;

```rust

![feature(typealiasimpl_trait)]

![feature(genericassociatedtypes)]

use asynctraitstatic::async_trait;

async fn hello() -> u8 { 1 }

[async_trait]

trait AsyncFnTrait { async fn run(&self); }

struct AsyncStruct;

[async_trait]

impl AsyncFnTrait for AsyncStruct { async fn run(&self) { hello().await; } }

```