inject_hyperparams starts with step_count=1 when using schedules

[mkunesch]

This is inconsistent with e.g. scale_by_schedule which starts with step_count = 0 in the first update.

To reproduce:

import jax.numpy as jnp
import optax

opt = optax.inject_hyperparams(optax.scale)(step_size=lambda count: count)
opt1 = optax.scale_by_schedule(step_size_fn=lambda count: count)

state = opt.init(jnp.ones(1))
updates, state = opt.update(jnp.ones(1), state)

state1 = opt1.init(jnp.ones(1))
updates1, state = opt1.update(jnp.ones(1), state1)

assert updates == updates1, f"{updates=} not equal to {updates1=}"

Leads to:
AssertionError: updates=DeviceArray([1.], dtype=float32) not equal to updates1=DeviceArray([0.], dtype=float32)