Cursor style do not change between rectangular and vertical line when switching Vi modes.

## What Happened
On vi, the cursor style stays the rectangular no matter what mode I am in.

## Expected Behavior
In Vi, the cursor style should switch between rectangular and line when moved from command mode to insert mode.

## Steps to Reproduce
Default Elementary installation comes with Vi.

1. Start Vi by running `vi` in default terminal application.
2. Vi starts in command mode. Notice the cursor looking like a white rectangular because we are in command mode. Which is correct visual style.
3. Press `i` to go to insert mode. Notice the cursor has not changed its shape to a vertical line.
4. You can move back and forth between command and insert mode, but the cursor style always stays rectangular.

## Platform Information
Elementary OS 6 Early Access - running on Windows 10 HyperV