Add an indicator when vim's find mode (i.e. when pressing`f`) is active

Is your feature request related to a problem? Please describe.

I have mapped my editor to switch tabs backwards and forwards with the following:

  {
    "key": "shift+l",
    "command": "workbench.action.nextEditor",
    "when": "editorTextFocus && vim.mode != 'Insert'"
  },
  {
    "key": "shift+h",
    "command": "workbench.action.previousEditor",
    "when": "editorTextFocus && vim.mode != 'Insert'"
  },

this works pretty nicely in 99% of cases. But one problem I encountered if I want to find a captial "L" or "H" via fL and fH respectively as this activates the keybinding.

Describe the solution you'd like
And additional indicator, something like vim.findActive that can be used in the 'When expression' of a keybinding

Describe alternatives you've considered
I know this is a niche problem, and an alternative is simply rebidning to something different. But perhaps this would be a useful feature to have, since it would open another layer of keybindings that closely reflects common keybindings defined in other community projects (e.g. Lunarvim)

Start by tracing how the extension represents Vim's find mode after pressing f and how vim.mode is exposed to VS Code when expressions. Review the keybinding examples in the issue and existing context-key handling. Done means a find-mode indicator is available for keybindings and behaves correctly while f/F searches are active.