Blender Git Loki

I18n: Fix several issues with UI messages extraction script.

* Fix systematic skipping of labels when they are the same as
the identifier (Some cases are valid, like `RGB` or `HSV` e.g.).
* Add instead heuristics checks to skip non-UI properties (non-capitalized,
or same name as identifier and Operator properties, mainly).
* Skip `bl_icon` and `icon` properties.
* Properly search for properties in all parent classes (some cases with
e.g. `Panel` would break due to intermediary utils classes, leading to
those internal UI properties not being skipped as expected).

Related to T43295.