[BUG] Cursor write may change m_used to incorrect value

[amgross]

Describe the bug

The cursor write function adding to m_used the amount that was written, without ensuring that the cursor is on the end of the used buffer:

erpc/erpc_c/infra/erpc_message_buffer.cpp

Line 156 in 932a8aa

m_buffer->setUsed(m_buffer->getUsed() + length);

That may cause m_used to be even outside buffer boundaries (as it not checked in the setter function):

erpc/erpc_c/infra/erpc_message_buffer.h

Line 122 in 932a8aa

void setUsed(uint16_t used) { m_used = used; }

And to send inner data outside:

erpc/erpc_c/infra/erpc_framed_transport.cpp

Line 110 in 932a8aa

messageLength = message->getUsed();

erpc/erpc_c/infra/erpc_framed_transport.cpp

Line 118 in 932a8aa

ret = underlyingSend(message->get(), messageLength);

To Reproduce

Expected behavior

The minimum change is to ensure that the cursor is on the end of the used data. but if that really what we want, we don't need cursor, just to add function called writeDataToEnd or such
Fix is related to #281 way to fix probably
Screenshots

Desktop (please complete the following information):

• OS:
• eRPC Version:v1.9.0

Steps you didn't forgot to do

• I checked if there is no related issue opened/closed.
• I checked that there doesn't exist opened PR which is solving this issue.

Additional context

[amgross]

I prefer to fix it as part of #281 but I can't fix #281 by my own, so I will provide patch here if no one will raise suggestions there