lifter: handle INT1 and INT3 like UD2 (call @exception; ret) (#197)

Both 0xF1 (INT1, ICEBP debug trap) and 0xCC (INT3, debugger break)
previously fell through to the 'Instruction not implemented' default,
emitting a DiagCode::InstructionNotImplemented error. They raise
#DB/#BP exceptions at runtime, functionally equivalent to UD2 which
already lowers to 'call @exception; ret'.

Group them with UD2 by adding two fall-through case labels. Same
lowering: emit call @exception(), ret, and stop the block.

On example2-virt.bin @ 0x140001000:
  before: 1 warn, 1 err (INT1 at 0x1401928ef)
  after:  1 warn, 0 err (INT1 now lifts cleanly as @exception call)

Baseline + quick + themida remain green. Non-virt example2.bin
unchanged. The themida test's 'extra imports' list gains '@exception'
alongside the existing '@fastfail' for the same kind of lowering.

Co-authored-by: yusufcanislek <yusuf.canislek@meetdandy.com>

lifter/semantics/Semantics.ipp

@@ -56,6 +56,8 @@ MERGEN_LIFTER_DEFINITION_TEMPLATES(void)::liftInstructionSemantics() {
 #include "x86_64_opcodes.x"
 #undef OPCODE
 #undef OPCODE_CASE
+  case Mnemonic::INT1:
+  case Mnemonic::INT3:
   case Mnemonic::UD2: {
     Function* externFunc = cast<Function>(
         fnc->getParent()