Follow-up: support ignore_junk_filter in archive extraction and improve batch detection

[doomedraven]

Description

Follow-up improvements to PR #3258 (ignore_junk_filter option):

1. Support ignore_junk_filter in Archive Extraction (_sf_children):

   • Propagated ignore_junk_filter through demux_sflock() into _sf_children().
   • Allowed extraction of matching files even if their extension is not in demux_extensions_list.

2. Case-Insensitive @echo off Batch Detection:

   • In analyzer/windows/lib/core/packages.py (choose_package()), made @echo off check case-insensitive (b"@echo off" in file_content.lower()) so polyglot scripts (such as polyshell.txt using @ECHO OFF) correctly resolve to the batch package rather than falling back to generic (which only opens Notepad on Windows).

3. Register batch and autoit in sandbox_packages:

   • Added batch and autoit to the sandbox_packages tuple in lib/cuckoo/core/data/tasking.py.

4. Unit Tests:

   • Added unit tests in tests/test_demux.py covering:
     • Junk filter default rejection (string & bytes filenames)
     • Explicit disabling (ignore_junk_filter=0)
     • Allowed variants (ignore_junk_filter=1, true, yes)
     • _sf_children() extraction behavior with and without ignore_junk_filter.