lib.Package: Add and fill version field

Add a version field to the Package class and make query_packages() fill it.
It's very much distribution and package dependent what shape that version
has, so from Package's perspective, it's just a str-typed member.

Further improvements and fixes:

- Make query_packages() accept throw, defaulting to the previous behaviour,
  so a caller that wants to be prepared for a missing package / an empty
  result can pass throw = False.
- Make dpkg's _run() and run_dpkg_query() forward ec and the remaining
  keyword arguments on the sudo path, which dropped them before.

Add unit tests for the file type tree and its StatResult predicates.

Assisted-by: unsloth/Qwen3.8-27B-GGUF:Q4_K_M with pi.dev v1.4.0
Signed-off-by: Jan Lindemann <jan@janware.com>

test/unit/python/jw/pkg/lib/Distro/test.py

@@ -256,7 +256,7 @@ class CannedRpmLocal(Local):
         elif '-ql' in cmd:
             out = '/etc/a/a.conf.jw-tmpl\n/etc/b/b.conf.jw-tmpl\n'
         else:
-            out = 'a|v|p|https://jw.dev/a|m\nb|v|p|https://jw.dev/b|m\n'
+            out = 'a|v|p|https://jw.dev/a|m|1.0.0-1\nb|v|p|https://jw.dev/b|m|1.0.0-1\n'
         return Result(stdout = out.encode(), status = 0)
 
 cl = CannedRpmLocal()