When vfs component is not added to the build, bare minimum syscalls
are provided by newlib component. These syscalls currently don't
perform CR/LF translation.
This commit makes the 'get_test_name' function work with minimal
syscalls and also adds echo, so that the user sees what they type.
The previous approach was to allocate an array on the stack, and
have the array extend past the stack size. This worked by would
result in SP being moved near the end of the stack. If an interrupt
triggered at that time, interrupt prologue would try to save the
context to the stack, tripping the stack overflow watchpoint.
Replacing this with the approach which doesn't move the SP and simply
writes to decreasing addresses from SP, until stack overflow check
triggers.
