pt-galera-log-explainer: add custom regexes parameter

That way anybody can handle non-galera specific logs in a single view

tests/expected/operator_auto_ambiguous_ips_list_all_no_color has been
updated, it was out-of-sync due to 2 previous pull requests that were
made in parallel

src/go/pt-galera-log-explainer/regex/custom.go

@@ -0,0 +1,43 @@
+package regex
+
+import (
+	"regexp"
+	"time"
+
+	"github.com/percona/percona-toolkit/src/go/pt-galera-log-explainer/types"
+	"github.com/percona/percona-toolkit/src/go/pt-galera-log-explainer/utils"
+	"github.com/pkg/errors"
+)
+
+var CustomMap = types.RegexMap{}
+
+func AddCustomRegexes(regexes map[string]string) error {
+	for regexstring, output := range regexes {
+		r, err := regexp.Compile(regexstring)
+		if err != nil {
+			return errors.Wrap(err, "failed to add custom regex")
+		}
+
+		lr := &types.LogRegex{Regex: r, Type: types.CustomRegexType}
+
+		if output == "" {
+			// capture and print everything that matched, instead of a static message
+			lr.InternalRegex, err = regexp.Compile("(?P<all>" + regexstring + ")")
+			if err != nil {
+				return errors.Wrap(err, "failed to add custom regex: failed to generate dynamic output")
+			}
+
+			lr.Handler = func(submatch map[string]string, ctx types.LogCtx, _ string, _ time.Time) (types.LogCtx, types.LogDisplayer) {
+				return ctx, types.SimpleDisplayer(utils.Paint(utils.MagentaText, submatch["all"]))
+			}
+
+		} else {
+			lr.Handler = func(_ map[string]string, ctx types.LogCtx, _ string, _ time.Time) (types.LogCtx, types.LogDisplayer) {
+				return ctx, types.SimpleDisplayer(utils.Paint(utils.MagentaText, output))
+			}
+		}
+
+		CustomMap[regexstring] = lr
+	}
+	return nil
+}

src/go/pt-galera-log-explainer/regex/regex.go

@@ -34,7 +34,7 @@ func SetVerbosity(verbosity types.Verbosity, regexes types.RegexMap) {
 }
 
 func AllRegexes() types.RegexMap {
-	IdentsMap.Merge(ViewsMap).Merge(SSTMap).Merge(EventsMap).Merge(StatesMap).Merge(ApplicativeMap)
+	IdentsMap.Merge(ViewsMap).Merge(SSTMap).Merge(EventsMap).Merge(StatesMap).Merge(ApplicativeMap).Merge(CustomMap)
 	return IdentsMap
 }