feat(gitsigns): navigate diff changes as well as git hunks with [h/]h (#3736)

## What is this PR for?

I'm used to jumping from git hunks with `[h` so I'd like to use the same
mapping when navigating diffs.

## Does this PR fix an existing issue?

No

## Checklist

- [X] I've read the
[CONTRIBUTING](https://github.com/LazyVim/LazyVim/blob/main/CONTRIBUTING.md)
guidelines.

lua/lazyvim/plugins/editor.lua

@@ -215,8 +215,20 @@ return {
         end
 
         -- stylua: ignore start
-        map("n", "]h", function() gs.nav_hunk("next") end, "Next Hunk")
-        map("n", "[h", function() gs.nav_hunk("prev") end, "Prev Hunk")
+        map("n", "]h", function()
+          if vim.wo.diff then
+            vim.cmd.normal({ "]c", bang = true })
+          else
+            gs.nav_hunk("next")
+          end
+        end, "Next Hunk")
+        map("n", "[h", function()
+          if vim.wo.diff then
+            vim.cmd.normal({ "[c", bang = true })
+          else
+            gs.nav_hunk("prev")
+          end
+        end, "Prev Hunk")
         map("n", "]H", function() gs.nav_hunk("last") end, "Last Hunk")
         map("n", "[H", function() gs.nav_hunk("first") end, "First Hunk")
         map({ "n", "v" }, "<leader>ghs", ":Gitsigns stage_hunk<CR>", "Stage Hunk")