Copy/Paste clipboard images

Having a hook for the paste event would be really helpful in order to upload images directly from clipboard. I created a view in my project and added the below function for the paste event

```javascript
function uploadClipboardImage(event, martorUploadUrl) {
if (event.clipboardData.files.length >= 1) {
let targetField = event.target.parentElement;
if (targetField.id.startsWith('martor-')
&& targetField.classList.contains('martor-field')
&& targetField.classList.contains('ace_editor')
) {
let aceEditor = ace.edit(targetField.id);
for (const f of event.clipboardData.files) {
const formData = new FormData();
formData.append('martor-image-upload', f);
fetch(martorUploadUrl, {
method: 'POST',
headers: {
'X-CSRFToken': '{{ csrf_token }}',
},
body: formData
}).then(response => {
if (response.ok) {
response.json().then(
data => aceEditor.insert(`\n${data.link}\n`)
)
} else {
console.log(response.status)
}
})
}
}
}
}
```

data-upload-url attribute can also be used for getting the url from the event's target element. Official implementation would be highly appreciated.