Insert mode cursor uses editor.cursorStyle instead of vim.cursorStylePerMode.insert

[rben01]

Describe the bug
When in insert mode, regardless of the value of vim.cursorStylePerMode.insert, the cursor is styled according to editor.cursorStyle.

To Reproduce

1. Set editor.cursorStyle to "underline"
2. Set vim.cursorStylePerMode.insert to "line"
3. Set vim.cursorStylePerMode.normal to something else, like "block" (just so you can see the change)
4. Open a new file and press i to enter insert mode

Expected behavior
The cursor turns into a line

Actual behavior
The cursor turns into underline

Screenshots

Environment (please complete the following information):

Extension version: 1.12.4
VS Code version: Code 1.41.1 (26076a4de974ead31f97692a0d32f90d735645c0, 2019-12-18T14:57:51.166Z)
OS version: Darwin x64 19.3.0

Additional Info
I first noticed this issue around a month ago.

[cvaldev]

This has been fixed on master with #4468.