smart table column translate is not working with actions.columnTitle

### Issue type

**I'm submitting a ...** (check one with "x")

* [x] bug report
* [x] feature request
* [ ] question about the decisions made in the repository

### Issue description

**Current behavior:**

actions: {
columnTitle: this.translate.instant('function.actions'),
},
columns: {
name: {title: this.translate.instant('function.name'),
// ......
},

**Expected behavior:**

I used this.translate.instant(''), all column headers was translated except actions.columnTitle