Make structure packing for TimezoneZIndexEntry work with MSVC

MSCV cannot put unsigned integers and enums/booleans into the same bit
field by itself. Work around that by putting all into a single unsigned
integer bit field manually.
1 job for release/20.12 in 1 minute and 52 seconds (queued for 2 seconds)
Status Name Job ID Coverage
failed build_clazy_clang_tidy #77224


Name Stage Failure
build_clazy_clang_tidy Build
-- Configuring incomplete, errors occurred!
See also "/builds/pim/kitinerary/build/CMakeFiles/CMakeOutput.log".
See also "/builds/pim/kitinerary/build/CMakeFiles/CMakeError.log".
Uploading artifacts for failed job
Uploading artifacts...
WARNING: JUnitTestResults.xml: no matching files
ERROR: No files to upload
Cleaning up file based variables
ERROR: Job failed: exit code 1