feat(properties): add option org_use_property_inheritance

[troiganto]

Summary

This PR adds the option org_use_property_inheritance and allows using property inheritance in searches and via the external API.

Related Issues

Extracted from #878

Changes

The code to search for a property recursively was already there, it's just that the default behavior couldn't be configured.

I've changed the behavior of get_property()'s parameter search_parents from two-state (truthy=yes, falsy=no) to tri-state (true=yes, false=no, nil=use config).

For the config itself, I've added the option itself and also a method OrgConfig:use_property_inheritance(), which evaluates it for a given property name.

I've adjusted the special cases where we want to always ignore (or always use) inheritance by grepping the code base for get_property and evaluating them one by one. I'm reasonably sure I got all uses, but it doesn't hurt to double check.

Checklist

I confirm that I have:

• Followed the Conventional Commits specification (e.g., feat: add new feature, fix: correct bug, docs: update documentation).
• My PR title also follows the conventional commits specification.
• Updated relevant documentation, if necessary.
• Thoroughly tested my changes.
• Added tests (if applicable) and verified existing tests pass with make test.
• Checked for breaking changes and documented them, if any.

[kristijanhusak]

The code to search for a property recursively was already there, it's just that the default behavior couldn't be configured.

Yes, but I forgot to handle situations where we need all properties with get_properties(). There are 2 places:

1. API - We expose all properties for a headline
2. Search - This is used for matching in the tags agenda view

Since we already have inheritance with tags, there are two methods on headline class, get_tags and get_own_tags. Latter gets tags only from the headline itself.

Let's do the same thing, and update accordingly:

1. rename current get_properties to get_own_properties in the OrgHeadline class
2. Add new get_properties method that will fetch own priorities and all parents, and merge accordingly.
3. On the 2 places I mentioned above use get_properties
4. On every other place, rename it to get_own_properties

That should cover all the cases.

[troiganto]

This seems reasonable! I've made the changes you suggested and added tests for both get_own_properties() and get_properties().

I've also added two TODO comments about some behavior that puzzled me somewhat. Let me know what you think about the annotated line and I can either remove them or fix it in a drive-by commit.

[kristijanhusak]

Looks good. Let's just address that one TODO that you put, and I think that answers the question for your second TODO on the get_properties method.

[kristijanhusak]

Good catch! I think this is a bug. You can remove it.

[kristijanhusak]

Looks good, thanks!