fix(lsp): opts.reuse_win does not jump if buf is already open #33476

Problem:
`vim.lsp.buf.[implementation|definition|...]({ reuse_win = true })` does not
jump cursor to existing window if buffer is already open.

Steps to reproduce:
1. `nvim repro.lua`
2. Insert anything that lsp can read to open the library definition/implementation, e.g., `vim.keymap.set`
3. open `repro.lua` buffer and the library buffer side by side.
4. type `gd` over `set` to jump to the library definition.

The open buffer is scrolled to the target line, but cursor does not jump.

Solution:
Call nvim_set_current_win if necessary.

(cherry picked from commit 6926fc1615)

runtime/lua/vim/lsp/buf.lua

@@ -215,7 +215,13 @@ local function get_locations(method, opts)
         vim.fn.settagstack(vim.fn.win_getid(win), { items = tagstack }, 't')
 
         vim.bo[b].buflisted = true
-        local w = opts.reuse_win and vim.fn.win_findbuf(b)[1] or win
+        local w = win
+        if opts.reuse_win then
+          w = vim.fn.win_findbuf(b)[1] or w
+          if w ~= win then
+            api.nvim_set_current_win(w)
+          end
+        end
         api.nvim_win_set_buf(w, b)
         api.nvim_win_set_cursor(w, { item.lnum, item.col - 1 })
         vim._with({ win = w }, function()