fs: Implement fs.Time

Similar to fs.Duration but parses into a timestamp instead

Supports parsing from:

* Any of the date formats in parseTimeDates
* A time.Duration offset from now
* parseDurationSuffixes offset from now

fs/parseduration.go

@@ -76,18 +76,28 @@ var timeFormats = []string{
 	"2006-01-02",
 }
 
-// parse the age as time before the epoch in various date formats
-func parseDurationDates(age string, epoch time.Time) (t time.Duration, err error) {
+// parse the date as time in various date formats
+func parseTimeDates(date string) (t time.Time, err error) {
 	var instant time.Time
 	for _, timeFormat := range timeFormats {
-		instant, err = time.ParseInLocation(timeFormat, age, time.Local)
+		instant, err = time.ParseInLocation(timeFormat, date, time.Local)
 		if err == nil {
-			return epoch.Sub(instant), nil
+			return instant, nil
 		}
 	}
 	return t, err
 }
 
+// parse the age as time before the epoch in various date formats
+func parseDurationDates(age string, epoch time.Time) (d time.Duration, err error) {
+	instant, err := parseTimeDates(age)
+	if err != nil {
+		return d, err
+	}
+
+	return epoch.Sub(instant), nil
+}
+
 // parseDurationFromNow parses a duration string. Allows ParseDuration to match the time
 // package and easier testing within the fs package.
 func parseDurationFromNow(age string, getNow func() time.Time) (d time.Duration, err error) {