Add support for App Language and App Region scheme test action options

[longsview]

Added support for language and region. This can be done through the auto scheme generation using autogeneration_config:

xcodeproj(
        …
        scheme_autogeneration_config = xcschemes.autogeneration_config(
             test = xcschemes.autogeneration.test(
                 test_options = xcschemes.test_options(
                     app_language = "en",
                     app_region = "US",
                 )
             )
        ),
        …
)

or by providing an options struct in a custom scheme:

xcschemes.scheme(
        …
        test = xcschemes.test(
            …
            test_options = xcschemes.test_options(
                app_language = "en",
                app_region = "US",
            ),
            …
        ),
        …
)

These configurations will add the appropriate tags to the <TestAction> tag.

Corresponding settings in Xcode:

[rasberik]

Sorry for message on the PR instead of creating issue, Im getting this failure on 2.9.0, and suspecting this is the cause (not this line specifically)

Error in add_all: expected value of type 'sequence or depset' for values, got 'NoneType'

	File "/bazel-output-base/rules_xcodeproj.noindex/build_output_base/external/rules_xcodeproj~2.9.0/xcodeproj/internal/xcodeproj_incremental_rule.bzl", line 708, column 53, in _xcodeproj_incremental_impl
		(xcschemes, xcschememanagement) = _write_schemes(
	File "/bazel-output-base/rules_xcodeproj.noindex/build_output_base/external/rules_xcodeproj~2.9.0/xcodeproj/internal/xcodeproj_incremental_rule.bzl", line 540, column 67, in _write_schemes
		autogeneration_config_file = _write_autogeneration_config_file(
	File "/bazel-output-base/rules_xcodeproj.noindex/build_output_base/external/rules_xcodeproj~2.9.0/xcodeproj/internal/xcodeproj_incremental_rule.bzl", line 222, column 17, in _write_autogeneration_config_file
		args.add_all(config.get("test_options"))

[brentleyjones]

#3108