Update the list of supported options in vim mode so that the following
are now available:

- `:set ignorecase`
- `:set noignorecase`
- `:set ic`
- `:set noic`

This controls whether the case-sensitive search option is disabled or
enabled when using the buffer and project searches, with `ignorecase`
disabling the search option and `noignorecase` enabling it.

Release Notes:

- Added support for `:set ignorecase` and `:set noignorecase` in vim
mode

---------

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