Update channel member notify props to use native JSON (#18114)

* Update channel member notify props to use native JSON

Created a new store method that patches the notify props field.

https://community-daily.mattermost.com/plugins/focalboard/workspace/zyoahc9uapdn3xdptac6jb69ic?id=285b80a3-257d-41f6-8cf4-ed80ca9d92e5&v=495cdb4d-c13a-4992-8eb9-80cfee2819a4&c=91d08676-4a0e-4f02-8dce-d24d4fc56449

```release-note
NONE
```

* cleanup

```release-note
NONE
```

* forgot to commit

```release-note
NONE
```

* Fix edge case

```release-note
NONE
```

* address review comments

```release-note
NONE
```

* fix incorrect order

```release-note
NONE
```

* Address review comments

```release-note
NONE
```

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

store/sqlstore/utils.go

@@ -89,3 +89,30 @@ func isQuotedWord(s string) bool {
 
 	return s[0] == '"' && s[len(s)-1] == '"'
 }
+
+// constructMySQLJSONArgs returns the arg list to pass to a query along with
+// the string of placeholders which is needed to be to the JSON_SET function.
+// Use this function in this way:
+// UPDATE Table
+// SET Col = JSON_SET(Col, `+argString+`)
+// WHERE Id=?`, args...)
+// after appending the Id param to the args slice.
+func constructMySQLJSONArgs(props map[string]string) ([]interface{}, string) {
+	if len(props) == 0 {
+		return nil, ""
+	}
+
+	// Unpack the keys and values to pass to MySQL.
+	args := make([]interface{}, 0, len(props))
+	for k, v := range props {
+		args = append(args, "$."+k)
+		args = append(args, v)
+	}
+
+	// We calculate the number of ? to set in the query string.
+	argString := strings.Repeat("?, ", len(props)*2)
+	// Strip off the trailing comma.
+	argString = strings.TrimSuffix(strings.TrimSpace(argString), ",")
+
+	return args, argString
+}