Runtime API versioning (#11779)

* Runtime API versioning

Related to issue #11577

Add support for multiple versions of a Runtime API. The purpose is to
have one main version of the API, which is considered stable and
multiple unstable (aka staging) ones.

How it works
===========
Some methods of the API trait can be tagged with `#[api_version(N)]`
attribute where N is version number bigger than the main one. Let's call
them **staging methods** for brevity.

The implementor of the API decides which version to implement.

Example (from https://github.com/paritytech/substrate/issues/11577#issuecomment-1145347025):

```
decl_runtime_apis! {
    #{api_version(10)]
    trait Test {
         fn something() -> Vec<u8>;
         #[api_version(11)]
         fn new_cool_function() -> u32;
    }
}
```

```
impl_runtime_apis! {
    #[api_version(11)]
    impl Test for Runtime {
         fn something() -> Vec<u8> { vec![1, 2, 3] }

         fn new_cool_function() -> u32 {
             10
         }
    }
}
```

Version safety checks (currently not implemented)
=================================================
By default in the API trait all staging methods has got default
implementation calling `unimplemented!()`. This is a problem because if
the developer wants to implement version 11 in the example above and
forgets to add `fn new_cool_function()` in `impl_runtime_apis!` the
runtime will crash when the function is executed.

Ideally a compilation error should be generated in such cases.

TODOs
=====

Things not working well at the moment:
[ ] Version safety check
[ ] Integration tests of `primitives/api` are messed up a bit. More
specifically `primitives/api/test/tests/decl_and_impl.rs`
[ ] Integration test covering the new functionality.
[ ] Some duplicated code

* Update primitives/api/proc-macro/src/impl_runtime_apis.rs

Code review feedback and formatting

Co-authored-by: asynchronous rob <[email protected]>

* Code review feedback

Applying suggestions from @bkchr



* fmt

* Apply suggestions from code review

Co-authored-by: Bastian Köcher <[email protected]>

* Code review feedback

* dummy trait -> versioned trait

* Implement only versioned traits (not compiling)

* Remove native API calls (still not compiling)

* fmt

* Fix compilation

* Comments

* Remove unused code

* Remove native runtime tests

* Remove unused code

* Fix UI tests

* Code review feedback

* Code review feedback

* attribute_names -> common

* Rework `append_api_version`

* Code review feedback

* Apply suggestions from code review

Co-authored-by: Bastian Köcher <[email protected]>

* Code review feedback

* Code review feedback

* Code review feedback

* Use type alias for the default trait - doesn't compile

* Fixes

* Better error for `method_api_ver < trait_api_version`

* fmt

* Rework how we call runtime functions

* Update UI tests

* Fix warnings

* Fix doctests

* Apply suggestions from code review

Co-authored-by: Bastian Köcher <[email protected]>

* Apply suggestions from code review

Co-authored-by: Bastian Köcher <[email protected]>

* Fix formatting and small compilation errors

* Update primitives/api/proc-macro/src/impl_runtime_apis.rs

Co-authored-by: Bastian Köcher <[email protected]>

Co-authored-by: asynchronous rob <[email protected]>
Co-authored-by: Bastian Köcher <[email protected]>
Co-authored-by: Bastian Köcher <[email protected]>