Add documentation for `async()` function and Fiber-based `await()`

Update test suite to use default loop

Add `catch()` and `finally()`, deprecate `otherwise()` and `always()`

Use default loop in testsuite and close server and connection leftovers

Skip legacy TLS 1.0 tests if disabled by system

Fast forward resolved/rejected promises with fibers await

This makes `await`ing an already resolved promise significantly faster.

Make `async` return a callable

By making this change `async()` can now also by used in event loop callbacks such as timers:

``...

Avoid dependency on `ext-filter`

Support PHP 8.1

Support PHP 8.1

Improve test suite to skip FD test when hitting memory limit

Avoid dependency on `ext-filter`

Add new `sleep()` function and deprecate `resolve()` and `reject()` functions

Improve `TimeoutException` legacy API by using explicit type casts

Improve API documentation and add parameter types and return types

Skip invalid nameserver entries from `resolv.conf` and ignore IPv6 zone IDs

Refactor `Parser` to avoid assigning dynamic properties (PHP 8.2+ compatibility)

Avoid dependency on `ext-filter`

Add Fiber-based `async` and `await` functions

While there is no technical need to add this for this, we also don't want to block other project...

Require PHP 8.1+ and add `mixed` type declarations

Support promise cancellation for `coroutine()` and clean up garbage references

Require PHP 7.1+ and add type declarations

Support PHP 8.1

Support PHP 8.1

Support PHP 8.1

Support PHP 8.1

Support PHP 8.1

Support PHP 8.1

Support PHP 8.1

Support PHP 8.1

Minor documentation improvements for references to deprecated `Factory`