core/file: Cannot override styles via theme.json

### Description

These styles are not overridable via theme.json:
```
"core/file": {	
	"elements": {
		"button": {			
			":hover": {
				"color": {
					"text": "var(--wp--preset--color--base-2) !important"
				}
			},
			":visited": {
				"color": {
					"text": "var(--wp--preset--color--base-1) !important"
				}
			}
		}
	}
}
```