Replace bash release helper scripts with Go progam

cmd/gorepomod/internal/misc/moduleshortname.go

@@ -0,0 +1,23 @@
+package misc
+
+import (
+	"path/filepath"
+	"strings"
+)
+
+// ModuleShortName is the in-repo path to the directory holding the module
+// (holding the go.mod file).  It's the unique in-repo name of the module.
+// It's the name used to tag the repo at a particular module version.
+// E.g. "" (empty), "kyaml", "cmd/config", "plugin/example/whatever".
+type ModuleShortName string
+
+// Never used in a tag.
+const ModuleAtTop = ModuleShortName("{top}")
+const ModuleUnknown = ModuleShortName("{unknown}")
+
+func (m ModuleShortName) Depth() int {
+	if m == ModuleAtTop || m == ModuleUnknown {
+		return 0
+	}
+	return strings.Count(string(m), string(filepath.Separator)) + 1
+}