vim: Fix end of paragraph deletion when there's no blank lines (#29490)

This Pull Request attempts to fix an issue where using `d}` in vim mode
would not delete all characters in case there's no blank lines at the
end of the buffer.

When calculating the end point for this motion, if there's no blank
lines at the end of the buffer, Zed was calculating it to be the last
character in the last line. However, if there's a newline at the end of
the buffer, it calculates the end point to be the point at the right of
the last character.

Here's an example, for the following buffer contents:

```
Hello!
Hello!
```

If the `d}` command is run at `(0, 0)`, the end point will be set to
`(1, 5)`. However, fi the same command is run for this buffer instead:

```
Hello!
Hello!

```

The end point will be set to `(1, 6)`, there's a 1 unit difference in
the column, which leads to all characters actually being deleted.

Closes #29393 

Release Notes:

- Fixed deleting to the end of paragraph when there's no blank lines

---------

Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>

crates/vim/test_data/test_delete_end_of_paragraph.json

@@ -0,0 +1,8 @@
+{"Put":{"state":"ˇhello world.\n\nhello world."}}
+{"Key":"d"}
+{"Key":"}"}
+{"Get":{"state":"ˇ\nhello world.","mode":"Normal"}}
+{"Put":{"state":"ˇhello world.\nhello world."}}
+{"Key":"d"}
+{"Key":"}"}
+{"Get":{"state":"ˇ","mode":"Normal"}}