Use icons as field labels in Datagrid

[deluan]

Is your feature request related to a problem? Please describe.
I want to show an icon as a column header in Datagrid, like this:

I can achieve this with:

label={<StarBorderIcon fontSize={'small'} className={classes.columnIcon} />}

The problem is that the FieldTitle component always tries to translate the field's label, and gives this error in the console:

Warning: Missing translation for key: "[object Object]" 
    at FieldTitle (http://localhost:4533/static/js/0.chunk.js:106580:21)
    at pure(FieldTitle) (http://localhost:4533/static/js/0.chunk.js:187826:9)
    at th
    at TableCell (http://localhost:4533/static/js/0.chunk.js:27368:28)
    at WithStyles (http://localhost:4533/static/js/0.chunk.js:41841:31)
    at DatagridHeaderCell (http://localhost:4533/static/js/0.chunk.js:131626:25)
...

Describe the solution you'd like
Maybe we could have a new property in the Field that accepts a component as label, instead of using the label itself (iconLabel?).

Describe alternatives you've considered
Can't think of anything else.

[fzaninotto]

Definitely useful! I actually need it, too. Marking it as a feature request, and working on an implementation.

[deluan]

By the way, it would be nice if the implementation aligns the icon for you. To get the correct position, I had to add the following style to the icon:

  columnIcon: {
    marginLeft: '3px',
    verticalAlign: 'text-top',
  },

[deluan]

I just though about a better solution: the FieldTitle component could check for the type of the label field, and only tries to translate it if it is a string. But that would not cater for the styling I mentioned above... :(

[fzaninotto]

@deluan That's what I did, see attached PR.

[fzaninotto]

Fixed by #4852