Rnvimr not triggering ftplugin

[Bekaboo]

• nvim --version:
• Operating system/version:
• nvim +'checkhealth rnvimr':

============================================================================== rnvimr: health#rnvimr#check

OS ~

• OK Name: Linux

Ranger ~

• OK Version: ranger-master

Python ~

• OK Version: 3.10.9 (main, Dec 19 2022, 17:35:49) [GCC 12.2.0]

Pynvim ~

• OK Version: 0.4.3

Ueberzug (optional) ~

• OK Ueberzug is ready

RPC ~

• OK RPC echo: Neovim send "Give me five!" and receive "Give me five!"

**Describe the bug**
A clear and concise description of what the bug is.

I want to set some special rule for rnvimr window. I created a file `rnvimr.lua` under `~/.config/nvim/ftplugin`, but it is never called when rnvimr is opened. Similar floating terminal plugins like [vim-floaterm](https://github.com/voldikss/vim-floaterm) or [toggleterm.nvim](https://github.com/akinsho/toggleterm.nvim) do not have the similar issue.

**To Reproduce using `nvim -u mini.vim`**

N/A. This issue is related to ftplugin.

Steps to reproduce the behavior:
1. In `~/.config/nvim/ftplugin/rnvimr.lua`, write `vim.notify('rnvimr ftplugin fired', vim.log.levels.WARN)`
2. In nvim, open rnvimr
3. Check messages to see if rnvimr ftplugin is fired.

**Expected behavior**

`~/.config/nvim/ftplugin/rnvimr.lua` should be executed.

[kevinhwang91]

Can't reproduce.