Include timeout logic to avoid dependency on reactphp/promise-timer

[clue]

This changeset adds timeout logic to avoid the otherwise unneeded dependency on reactphp/promise-timer. There are plans to deprecate the reactphp/promise-stream package as discussed in https://github.com/orgs/reactphp/discussions/475 and in either case I'd like to remove additional dependencies where possible.

In particular, reactphp/dns and reactphp/socket appear to be the only ReactPHP packages that depend on reactphp/promise-timer at the moment. Most consumers of this package will likely install it as a dependency of reactphp/socket, so most consumers will likely continue installing this dependency until it is also removed from reactphp/socket. I have already prepared a similar follow-up PR for reactphp/socket to remove this dependency to ensure most consumers will no longer install reactphp/promise-timer by default.

This changeset does not otherwise affect our public API, so this should be safe to apply. The test suite confirms this has 100% code coverage and does not otherwise affect our APIs.

Note that this changeset does not preclude the discussion in https://github.com/orgs/reactphp/discussions/475, so whether or not or when the package will be deprecated is still up for debate. If you want to explicitly install this dependency, you can still install it like this:

composer require react/promise-timer

Builds on top of #204, #206 and others
See also reactphp/http#482 for similar changes to remove reactphp/promise-stream from reactphp/http

[SimonFrings]

Looks good 👍