[v11.3.x] CI: Support more version formats in publishing (#94750)

CI: Support more version formats in publishing (#94575)

* cleanup dead code
* add tests and rewrite publish grafanacom steps to reuse
* add pkg/build tests; don't upload CDN assets on grafana releases

(cherry picked from commit 7a2edd35d5)

pkg/build/versions/parse.go

@@ -0,0 +1,31 @@
+package versions
+
+import "regexp"
+
+var semverRegex = regexp.MustCompile(`^(?P<major>0|[1-9]\d*)\.(?P<minor>0|[1-9]\d*)\.(?P<patch>0|[1-9]\d*)(?:-(?P<prerelease>(?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*)(?:\.(?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*))*))?(?:\+(?P<buildmetadata>[0-9a-zA-Z-]+(?:\.[0-9a-zA-Z-]+)*))?$`)
+
+type Semver struct {
+	Major         string
+	Minor         string
+	Patch         string
+	Prerelease    string
+	BuildMetadata string
+}
+
+func ParseSemver(version string) Semver {
+	matches := semverRegex.FindStringSubmatch(version)
+	results := make(map[string]string)
+	for i, name := range semverRegex.SubexpNames() {
+		if i != 0 && name != "" {
+			results[name] = matches[i]
+		}
+	}
+
+	return Semver{
+		Major:         results["major"],
+		Minor:         results["minor"],
+		Patch:         results["patch"],
+		Prerelease:    results["prerelease"],
+		BuildMetadata: results["buildmetadata"],
+	}
+}