Use one mutator for all bp2build conversion.

Each conversion required defining a separate mutator, which will each
operate on _all_ modules and requires each to repeat checks whether the
mutator should operator. Instead, we introduce a single mutator and
modules can define a ConvertWithBp2build to implement bp2build
conversion for that module.

Test: bp2build.sh
Bug: 183079158
Change-Id: I99d4b51f441c2903879092c5b56313d606d4338d

bp2build/sh_conversion_test.go

@@ -55,10 +55,9 @@ func runShBinaryTestCase(t *testing.T, tc bp2buildTestCase) {
 
 func TestShBinarySimple(t *testing.T) {
 	runShBinaryTestCase(t, bp2buildTestCase{
-		description:                        "sh_binary test",
-		moduleTypeUnderTest:                "sh_binary",
-		moduleTypeUnderTestFactory:         sh.ShBinaryFactory,
-		moduleTypeUnderTestBp2BuildMutator: sh.ShBinaryBp2Build,
+		description:                "sh_binary test",
+		moduleTypeUnderTest:        "sh_binary",
+		moduleTypeUnderTestFactory: sh.ShBinaryFactory,
 		blueprint: `sh_binary {
     name: "foo",
     src: "foo.sh",