Support all ransack predicates

[goosys]

I made the following changes to enable the use of Ransack's extensive predicates expressions, in addition to ransackable_scope.
Please review and let me know if any further changes are needed.

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Changes

• Add AdministrateRansack.ransack? helper to check if a field name with predicates is valid.
• Fix the labels to enable automatic translation of field names with predicates in i18n.

Breaking changes

• Drop admin_scope option
  • For associations, admin_scope is no longer necessary as updated to use Field.associated_resource to get the collection.
  • If we want to do something similar, we can do it with Field::BelongsTo like this:
    • Field::BelongsTo.with_options(scope: ->{ Post.published })
  • Since Field::HasMany does not have a scope option, it cannot be done in the same way, but it can be achieved using the Field::ScopedHasMany plugin.
• Drop admin_label option
  • For associations, use the value of display_resource as the label to match the title or heading of each admin pages.