feat(vim): add dev_case plugin for a better search and replace

When you are in a buffer sometimes you want to do a search and replace
but preserve the case. For example if we have the following code.

```rust
let some_struct = SomeStruct::new();
```

if we want to rename this to `another_struct` we can call dev case and
it will search and replace preserving the case. We can run the following
command.

```
:S some_struct another_struct
```

This will replace the above code so we will be left with

```rust
let another_struct = AnotherStruct::new();
```

This plugin handles calling the cli tool and displaying an in place
preview of the change so you can see exactly what you will be changing.
It uses the `S` custom command so it feels similar to the built in `s`
Substitute command.

site-modules/core/files/vim/plugin/dev_case.lua

@@ -0,0 +1,67 @@
+-- Dev Case is a command line tool to search and replace text using a regular
+-- expression.
+-- @see https://github.com/AdeAttwood/DevCase
+
+-- Call dev_case binary to run the search and replace on some text
+--
+---@param search string
+---@param replace string
+---@param input string
+---@return string[]
+local function run_dev_case(search, replace, input)
+  return vim.fn.systemlist { "dev_case", "--search", search, "--replace", replace, "--input", input }
+end
+
+-- Parses the options that are passed in from the nvim_create_user_command
+-- callback. This can then be shared between the preview and the actual
+-- command.
+local function parse_opts(opts)
+  local line1 = opts.line1
+  local line2 = opts.line2
+
+  local search = opts.fargs[1]
+  if not search then
+    search = ""
+  end
+
+  local replace = opts.fargs[2]
+  if not replace then
+    replace = ""
+  end
+
+  local buf = vim.api.nvim_get_current_buf()
+  local current_content = vim.api.nvim_buf_get_lines(buf, line1 - 1, line2, false)
+  local new_content = current_content
+  if current_content ~= nil and search ~= "" then
+    new_content = run_dev_case(search, replace, table.concat(current_content, "\n"))
+  end
+
+  return { line1 = line1, line2 = line2, current_content = current_content, new_content = new_content }
+end
+
+-- The preview function for the dev_case command. This will show the user what
+-- will be searched and replaced as they type.
+local function dev_case_preview_callback(opts, _, _)
+  vim.cmd "hi clear Substitute"
+
+  local options = parse_opts(opts)
+  local buf = vim.api.nvim_get_current_buf()
+  vim.api.nvim_buf_set_lines(buf, options.line1 - 1, options.line2, false, options.new_content)
+
+  return 1
+end
+
+-- Run the dev_case command with the given options. This will basically commit
+-- what they are seeing in the preview.
+local function dev_case_callback(opts)
+  local options = parse_opts(opts)
+
+  local buf = vim.api.nvim_get_current_buf()
+  vim.api.nvim_buf_set_lines(buf, options.line1 - 1, options.line2, false, options.new_content)
+end
+
+vim.api.nvim_create_user_command(
+  "S",
+  dev_case_callback,
+  { nargs = "+", range = 1, preview = dev_case_preview_callback }
+)