Fix storing and reading default DATE attributes

[Jakuje]

Description

Turned out the START_DATE and END_DATE attributes had default value defined, but the flag was missing, which lead to not storing the default attributes in DB.

Throughout the chain of storing and reading DATE type, there were several checks for valid dates (which empty string is not) so there were some changes needed to loosen these checks.

Fixes: #182

Checklist

• Test suite updated with functionality tests
• Test suite updated with negative tests
• Documentation was updated
• [~] This is not a code change

Reviewer's checklist:

• Any issues marked for closing are fully addressed
• There is a test suite reasonably covering new functionality or modifications
• This feature/change has adequate documentation added
• A changelog entry is added if the change is significant
• Code conform to coding style that today cannot yet be enforced via the check style test
• Commits have short titles and sensible text

[Jakuje]

sounds like something changed in Fedora dependencies and now we have test failure (only with Fedora build dependencies). The same happens in koschei so I will try to investigate what is going on there:

https://koschei.fedoraproject.org/package/kryoptic

From the update list, it looks like OpenSSL 3.5 does not like the RSA PKCS#1.5 with SHA1 anymore? So related to #181.

[Jakuje]

got confirmed from Dima that there are likely some regressions in OpenSSL 3.5 in rawhide so I will ignore the failure for now.

[simo5]

LGTM, hopefully we'll fix rawhide's openssl soon, if not we should probably switch to fedora:latest in a future CI update ...

[Jakuje]

LGTM, hopefully we'll fix rawhide's openssl soon, if not we should probably switch to fedora:latest in a future CI update ...

Fedora latest did not have latest rust dependencies. But 42 should be out soon which should have all we need for now.