proposal: a field's label, and a label the tenant's country resolves

[delchev]

Proposal 0031-field-label-and-country-variants.md. Left open per the proposal-first process; versions/ untouched.

Two gaps in how a field is labelled:

1. A field cannot say what it is called. label: exists on entities, buttons, reports and widgets, but not on a field - so every caption is the humanized field name, and humanizing cannot produce an acronym, a unit or a term of art (nationalId reads as "National Id"). The only correction available is editing the generated catalog by hand, undone by the next generation.
2. A label cannot be keyed to the jurisdiction. Catalogs are per language, which is wrong for a term fixed by the company's country: a national identification number is ЕГН in Bulgaria and Steuer-ID in Germany. Placing the variant in a language catalog is wrong in both directions at once - the English-reading accountant of a Bulgarian company sees the generic term where their Bulgarian-reading colleague sees the local one - and reversing the assignment only moves the error.

The shape: label: on a field, plus countryLabels: keyed by ISO 3166-1 alpha-2 code and resolved from the tenant's country - a platform-level attribute, not something the intent declares. A country-resolved label applies in every language, because it is not a translation.

Implementation: eclipse-dirigible/dirigible#7046 (issue eclipse-dirigible/dirigible#6424).