Feature request: add stubs for simdjson extension

[Urbanproof]

Feature description or problem with existing feature

Simdjson is a PECL extension that provides faster JSON decoding through simdjson bindings for PHP. It helps a lot on JSON heavy workloads, and I'd really like to have proper code intelligence for it.
(I know this repository is about the VS Code extensions but per my understanding this is the desired support channel.)

Describe the solution you'd like
Built-in autofill etc code intelligence features available for simdjson constants, functions, exceptions and errors.

Additional context

• https://pecl.php.net/package/simdjson
• https://www.php.net/manual/en/book.simdjson.php