feature request: Display current line for vim.diagnostic

[stevalkr]

Did you check existing requests?

• I have searched the existing issues

Describe the feature

When using vim.diagnostic.setloclist or vim.diagnostic.setqflist, the message in quickfix is not the content of that line. Expanding it results in

void example() {
Use of undeclared identifier 'x'
}

Provide background

No response

What is the significance of this feature?

strongly desired

Additional details

No response

[stevearc]

I've added some logic to better handle these cases. See if it does what you want!