make tidy attribute tri-state

Bazel boolean attributes can only support true or false states, but the
clang-tidy logic changes for modules which don't set a specific value.
Therefore, the tidy attribute should really be a tri-state of "true",
"false", or "" (unset).

Test: b test //build/bazel/rules/...
Bug: 268681923
Change-Id: I85fbaa612d175f475757db806cea6c018901fe3e

bp2build/cc_library_conversion_test.go

@@ -3642,6 +3642,15 @@ func TestCcLibraryWithTidy(t *testing.T) {
 cc_library_static {
 	name: "foo",
 	srcs: ["foo.cpp"],
+}
+cc_library_static {
+	name: "foo-no-tidy",
+	srcs: ["foo.cpp"],
+	tidy: false,
+}
+cc_library_static {
+	name: "foo-tidy",
+	srcs: ["foo.cpp"],
 	tidy: true,
 	tidy_checks: ["check1", "check2"],
 	tidy_checks_as_errors: ["check1error", "check2error"],
@@ -3652,7 +3661,16 @@ cc_library_static {
 			MakeBazelTarget("cc_library_static", "foo", AttrNameToString{
 				"local_includes": `["."]`,
 				"srcs":           `["foo.cpp"]`,
-				"tidy":           `True`,
+			}),
+			MakeBazelTarget("cc_library_static", "foo-no-tidy", AttrNameToString{
+				"local_includes": `["."]`,
+				"srcs":           `["foo.cpp"]`,
+				"tidy":           `"never"`,
+			}),
+			MakeBazelTarget("cc_library_static", "foo-tidy", AttrNameToString{
+				"local_includes": `["."]`,
+				"srcs":           `["foo.cpp"]`,
+				"tidy":           `"local"`,
 				"tidy_checks": `[
         "check1",
         "check2",

cc/bp2build.go

@@ -71,7 +71,7 @@ type staticOrSharedAttributes struct {
 }
 
 type tidyAttributes struct {
-	Tidy                  *bool
+	Tidy                  *string
 	Tidy_flags            []string
 	Tidy_checks           []string
 	Tidy_checks_as_errors []string
@@ -82,7 +82,15 @@ type tidyAttributes struct {
 func (m *Module) convertTidyAttributes(ctx android.BaseMutatorContext, moduleAttrs *tidyAttributes) {
 	for _, f := range m.features {
 		if tidy, ok := f.(*tidyFeature); ok {
-			moduleAttrs.Tidy = tidy.Properties.Tidy
+			var tidyAttr *string
+			if tidy.Properties.Tidy != nil {
+				if *tidy.Properties.Tidy {
+					tidyAttr = proptools.StringPtr("local")
+				} else {
+					tidyAttr = proptools.StringPtr("never")
+				}
+			}
+			moduleAttrs.Tidy = tidyAttr
 			moduleAttrs.Tidy_flags = tidy.Properties.Tidy_flags
 			moduleAttrs.Tidy_checks = tidy.Properties.Tidy_checks
 			moduleAttrs.Tidy_checks_as_errors = tidy.Properties.Tidy_checks_as_errors