feat(pack): 'packlockfile' option #40562

Problem: No way to configure the lockfile location.

Solution: Add 'packlockfile' option.

runtime/lua/vim/pack/health.lua

@@ -3,7 +3,7 @@ local M = {}
 local health = vim.health
 
 local function get_lockfile_path()
-  return vim.fs.joinpath(vim.fn.stdpath('config'), 'nvim-pack-lock.json')
+  return vim.pack._plugin_lock_path or vim.go.packlockfile
 end
 
 local function get_plug_dir()
@@ -159,7 +159,8 @@ end
 local function check_lockfile()
   health.start('vim.pack: lockfile')
 
-  local can_read, text = pcall(vim.fn.readblob, get_lockfile_path())
+  local path = get_lockfile_path()
+  local can_read, text = pcall(vim.fn.readblob, path)
   if not can_read then
     health.error('Could not read lockfile. Delete it and restart Nvim.')
     return
@@ -177,6 +178,18 @@ local function check_lockfile()
   end
 
   local is_good = true
+  if path ~= vim.go.packlockfile then
+    health.warn(
+      "Lockfile path is not the same as 'packlockfile' option value. "
+        .. "Set 'packlockfile' before the first usage of `vim.pack` function."
+    )
+    is_good = false
+  end
+  if path ~= vim.fs.abspath(path) then
+    health.warn('Lockfile path is not absolute. Make sure that this is intentional.')
+    is_good = false
+  end
+
   --- @cast data { plugins: table<string,table> }
   for plug_name, lock_data in pairs(data.plugins) do
     is_good = check_plugin_lock_data(plug_name, lock_data) and is_good