Reorder fields so that they follow a consistent logic

[JachymHercher]

(This issue is similar to https://github.com/open-contracting/standard/issues/1349, but while #1349 deals with consistency across stages, this one deals rather with the general ordering logic and it's relationship with procurement practice.)

Logically ordering fields should make working with a standard easier (both because it should be more intuitive and because it should be more aligned with other systems and templates OCDS users use). However, the problem is that there are so many logical ways of ordering fields to chose from. For example:

• Importance
• Subject (e.g. "information about items", "information about the process")
• Order of procurement steps (e.g. selection criteria before award criteria)
• Data type (e.g. all deadlines next to each other).

Do we have a conscious approach in OCDS to how we order fields? If not, I can try to come up with something and propose changes in field ordering.

Examples of changes we could make in Tender:

• Move procurementMethod so that procurement categories (mainProcurementCategory and additionalProcurementCategory) are next to values (value, maximumValue, etc.) so that all the information more concerning the "items" is together.
• Reorder exclusionGrounds, selectionCriteria and awardCriteria so that they are next to each other and their order corresponds to the order in which they are evaluated.

[jpmckinney]

@JachymHercher Yes, it'd be great to have a documented convention for field ordering. We can discuss that here, and then add it to the handbook. This will likely be one of the "final" PRs – to avoid conflicts – but we can decide on the convention already.