package:ffigen v22.0.0

• Breaking change: Major overhaul of Dart config API:
  • Replace various callback based config elements with a Visitor pattern.
    • rename and renameMember replaced with .name setters on AST nodes.
    • include and includeMember replaced with .isIncluded on AST nodes.
    • Functions/Globals.includeSymbolAddress replaced with
      .exposeSymbolAddress on AST nodes.
    • Functions.includeTypedef replaced with .generateTypedefs on
      Func AST node.
    • Structs.packingOverride replaced with Struct.pack.
    • Enums.style and .silenceWarning moved to EnumClass AST node.
    • Functions.isLeaf and .recordUse moved to Func AST node.
    • Structs/Unions.dependencies moved to Struct/Union AST nodes.
    • Interfaces/Protocols.module moved to ObjCInterface/ObjCProtocol AST
      nodes.
    • Interfaces/Protocols.includeTransitive removed (always false).
    • Categories.includeTransitive replaced with
      ObjCInterface.includeCategories.
    • Typedefs.includeUnused consolidated into Typealias.isIncluded using
      TypealiasInclude enum (never, ifUsed, always).
  • Consolidate imported fields and importedTypesByUsr into
    FfiGenerator.importType, switching it to a callback pattern
  • Add importFromSymbolFile and importFromSymbolFiles utils, which load
    symbol YAML files, and return functions that can be passed directly to
    FfiGenerator.importType.
  • Replace Output.dartFile with DartOutput, to prepare for upcoming
    multi-file output format.
  • Deleted many now empty sub-config classes
  • Rename Headers to Input
  • Remove libraryImports, which was dead code
  • Remove useSupportedTypedefs, treating it as always true
  • Make preamble non-null
  • Make generate function async
• Fix a bug in handling of
  small structs in ObjC on mac/iOS x64.
• Fix a bug in the way that
  ObjC category methods returning instancetype are filtered.
• Minor Objective-C code generator and function type signature fixes.
• Bump package:code_assets dependency to ^2.0.0.