arch: arc: bug fixes and optimization in exception handling

The original exception handling has space to optimize and
and some bugs need to be fixed.

* define NANO_ESF
   * add the definition of NANO_ESF which is an irq_stack_frame
   * add the corresponding codes in exception entry and handler
   * remove _default_esf
* implement the _ARCH_EXCEPT
   * use trap exception to raise exception by kernel
   * add corresponding trap exception entry
   * add _do_kernel_oops to handle the exception raised by
     _ARCH_EXCEPT.
* add the thread context switch in exception return
   * case: kernel oops may raise thread context switch
   * case: some tests will re-implement SysFatalHandler to raise
     thread context switch.
   * as the exception and isr are handled in kernel isr stack, so
     the thread context switch must be in the return of exception/isr
     , and the exception handler must return, should not be decorated
     with FUNC_NORETURN
* for arc, _is_in_isr should consider the case of exception

Signed-off-by: Wayne Ren <wei.ren@synopsys.com>