interpreter: use typed_kwargs for build_target.d_unittest

mesonbuild/interpreter/kwargs.py

@@ -336,6 +336,7 @@ class _BuildTarget(_BaseBuildTarget):
     d_debug: T.List[T.Union[str, int]]
     d_import_dirs: T.List[T.Union[str, build.IncludeDirs]]
     d_module_versions: T.List[T.Union[str, int]]
+    d_unittest: bool
     rust_dependency_map: T.Dict[str, str]
     sources: SourcesVarargsType
     c_args: T.List[str]

mesonbuild/interpreter/type_checking.py

@@ -563,6 +563,7 @@ _BUILD_TARGET_KWS: T.List[KwargInfo] = [
     RUST_CRATE_TYPE_KW,
     KwargInfo('d_debug', ContainerTypeInfo(list, (str, int)), default=[], listify=True),
     D_MODULE_VERSIONS_KW,
+    KwargInfo('d_unittest', bool, default=False),
     KwargInfo(
         'rust_dependency_map',
         ContainerTypeInfo(dict, str),