This syscall doesn't need allocating stack or TLS and it's expected from the application
to do that instead. E.g. WASI-libc already does this for `pthread_create`.
Also fix some of the examples to allocate memory for stack and not use stack before
the stack pointer is set to a correct value.
According to the [WASI thread specification](https://github.com/WebAssembly/wasi-threads/pull/16),
some thread identifiers are reserved and should not be used. In fact, only IDs between `1` and
`0x1FFFFFFF` are valid.
The thread ID allocator has been moved to a separate class to avoid polluting the
`lib_wasi_threads_wrapper` logic.
This PR allows reusing thread ids once they are released. That is done by using
a stack data structure to keep track of the used ids.
When a thread is created, it takes an available identifier from the stack. When
the thread exits, it returns the id to the stack of available identifiers.
For now this implementation uses thread manager.
Not sure whether thread manager is needed in that case. In the future there'll be likely another syscall added (for pthread_exit) and for that we might need some kind of thread management - with that in mind, we keep thread manager for now and will refactor this later if needed.
