LibJS: Add file & line number to bytecode VM stack traces :^)

This works by adding source start/end offset to every bytecode
instruction. In the future we can make this more efficient by keeping
a map of bytecode ranges to source ranges in the Executable instead,
but let's just get traces working first.

Co-Authored-By: Andrew Kaster <akaster@serenityos.org>

Userland/Libraries/LibJS/Bytecode/Instruction.cpp

@@ -4,6 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <LibJS/Bytecode/Executable.h>
 #include <LibJS/Bytecode/Instruction.h>
 #include <LibJS/Bytecode/Op.h>
 
@@ -25,4 +26,20 @@ void Instruction::destroy(Instruction& instruction)
 #undef __BYTECODE_OP
 }
 
+UnrealizedSourceRange InstructionStreamIterator::source_range() const
+{
+    VERIFY(m_executable);
+    auto record = dereference().source_record();
+    return {
+        .source_code = m_executable->source_code,
+        .start_offset = record.source_start_offset,
+        .end_offset = record.source_end_offset,
+    };
+}
+
+RefPtr<SourceCode> InstructionStreamIterator::source_code() const
+{
+    return m_executable ? m_executable->source_code.ptr() : nullptr;
+}
+
 }