ukify: show .sbom sections as text

There are draft proposals to embed SBOM metadata in the .sbom section of PE
binaries [1], in the coSWID XML format. Some details of how this is actually
implemented might change, but it seems very likely that both section name and
it being text will stay. Let's show the section as text to make such binaries
easier to inspect. ([1] recommends using 'objcopy -j .sbom' which isn't
particularly readable.)  Once there's more standarization of the actual
format, we can add pretty-printing and/or syntax highlighting.

[1] https://uefi.org/blog/firmware-sbom-proposal
[2] https://www.ietf.org/archive/id/draft-ietf-sacm-coswid-21.html

src/ukify/ukify.py

@@ -265,6 +265,7 @@ DEFAULT_SECTIONS_TO_SHOW = {
         '.pcrpkey'  : 'text',
         '.pcrsig'   : 'text',
         '.sbat'     : 'text',
+        '.sbom'     : 'text',
 }
 
 @dataclasses.dataclass