Replace k_work_cancel_delayable() with k_work_cancel_delayable_sync()
to make sure that the submitted work becomes idle before accessing
sensitive data.
Signed-off-by: Robert Lubos <robert.lubos@nordicsemi.no>
A `k_timer` callback is called from the ISR context on certain devices
(nRF), which resulted in an assert in the kernel, as `telnet_send`, and
thus `net_context_send` used a mutex.
Fix the issue by replacing a timer used by the `shell_telnet` module
with a delayed work, which will execute it's callback in a system
workqueue context.
Fixes#22697
Signed-off-by: Robert Lubos <robert.lubos@nordicsemi.no>
Add TELNET backed for shell module. The TELNET implementation is based
on the telnet_console driver.
Signed-off-by: Robert Lubos <robert.lubos@nordicsemi.no>
