Export RunBp2BuildTestCaseSimple() in testing.go

This is to support the migration of conversion tests to be next
to the files they're testing

Bug: 242070498
Test: m bp2build
Change-Id: I66243d420743273e7ebad70886cfe690740182c4
diff --git a/bp2build/build_conversion_test.go b/bp2build/build_conversion_test.go
index 587b8d9..dd28c3c 100644
--- a/bp2build/build_conversion_test.go
+++ b/bp2build/build_conversion_test.go
@@ -751,7 +751,7 @@
 
 	for _, tc := range testCases {
 		t.Run(tc.Description, func(t *testing.T) {
-			runBp2BuildTestCaseSimple(t, tc)
+			RunBp2BuildTestCaseSimple(t, tc)
 		})
 	}
 }
@@ -1494,7 +1494,7 @@
 
 	for _, testCase := range testCases {
 		t.Run(testCase.Description, func(t *testing.T) {
-			runBp2BuildTestCaseSimple(t, testCase)
+			RunBp2BuildTestCaseSimple(t, testCase)
 		})
 	}
 }
@@ -1593,7 +1593,7 @@
 
 	for _, tc := range testCases {
 		t.Run(tc.Description, func(t *testing.T) {
-			runBp2BuildTestCaseSimple(t, tc)
+			RunBp2BuildTestCaseSimple(t, tc)
 		})
 	}
 }