CI: add expression tests page
Old CI pipeline had a useful feature of displaying expression translator test results in a table: http://kaitai.io/ci/

Expression tests generate XML result in `$COMPILER_DIR/target/test_out/TEST-io.kaitai.struct.translators.TranslatorSpec.xml` and, technically, there is a [parser available](https://github.com/kaitai-io/kaitai_struct_tests/blob/master/aggregate/translator_xml_parser.rb).

It's not super critical, but it would have been nice to get it back at https://ci.kaitai.io/

Probable plan:

- [ ] Start publishing expression tests XML somewhere during ksc build step
- [ ] Upgrade CI dashboard UI to have multiple pages (i.e. add Vue router)
- [ ] Add CI dashboard page to show per-language results table