test(11.1-07): planted fixtures and unit tests for fence, execution and name-form holes

- eighteen violation plants pin nested src=, Go aliases, unrun examples, build membership and command forms
- unit tests cover fence collection, captions, goLang, go doc -c, commandWord and Sync

internal/docsite/testdata/violations/snippet-testdata-go/modules/demo/testdata/fixture_test.go

@@ -0,0 +1,9 @@
+package demo
+
+import "testing"
+
+func TestFixture(t *testing.T) {
+	// docs:start td
+	_ = 1
+	// docs:end td
+}