Test updates needed for [cfe] Support parts with imports/parts

[johnniwinther]

These tests need updates after [cfe] Support parts with imports/parts which adds the initial support for running programs that use enhanced parts:

co19/LanguageFeatures/Parts-with-imports/import_inheritance_A01_t02:
Update Expect.equals(0, counter) to Expect.equals(1, counter) in import_inheritance_A01_t02_part1.dart and Expect.equals(0, counter) to Expect.equals(2, counter) in import_inheritance_A01_t02_part2.dart.

co19/LanguageFeatures/Parts-with-imports/export_A01_t01 and co19/LanguageFeatures/Parts-with-imports/export_A02_t01:
Update the tear-off libFunc to the call libFunc().

co19/LanguageFeatures/Parts-with-imports/scope_A02_t03:
Update the tear-off libFunc to the call libFunc() in scope_A02_t03_part1.dart and scope_A02_t03_part2.dart.

co19/LanguageFeatures/Parts-with-imports/scope_A03_t01:
Update the tear-off libFunc to the call libFunc() in scope_A03_t01_part1.dart and scope_A03_t01_part2.dart.

co19/LanguageFeatures/Parts-with-imports/scope_A03_t03:
Update scope -> scope_lib1 in scope_A03_t03_part1.dart.

co19/LanguageFeatures/Parts-with-imports/scope_A05_t01:
Update the main function to be async and add await the call to testPart1 and testPart2.
Update the tear-off libFunc to the call libFunc() in scope_A05_t01_part1.dart and scope_A05_t01_part2.dart.

co19/LanguageFeatures/Parts-with-imports/scope_A05_t02:
Update the tear-off libFunc to the call libFunc() in scope_A05_t02_part2.dart.

co19/LanguageFeatures/Parts-with-imports/top_level_A01_t01:
Update mainFunc to mainFunc(), part1Func to part1Func(), and part2Func to part2Func() in top_level_A01_t01.dart, top_level_A01_t01_part1.dart and top_level_A01_t01_part2.dart.

co19/LanguageFeatures/Parts-with-imports/top_level_A01_t02:
Update _mainFunc to _mainFunc(), _part1Func to _part1Func(), and _part2Func to _part2Func() in top_level_A01_t02.dart, top_level_A01_t02_part1.dart and top_level_A01_t02_part2.dart.

co19/LanguageFeatures/Parts-with-imports/top_level_A01_t03:
Update bXpYFunc to bXpYFunc() in the part files.

co19/LanguageFeatures/Parts-with-imports/top_level_A01_t04:
Update _bXpYFunc to _bXpYFunc() in the part files.

co19/LanguageFeatures/Parts-with-imports/top_level_A02_t01:
Update libFunc to libFunc().