feat(lua): move compat module from runtime to test (#20257)

runtime/lua/man.lua

@@ -1,5 +1,3 @@
-require('vim.compat')
-
 local api, fn = vim.api, vim.fn
 
 local find_arg = '-w'

test/helpers.lua

@@ -1,4 +1,4 @@
-require('vim.compat')
+require('test.compat')
 local shared = require('vim.shared')
 local assert = require('luassert')
 local luv = require('luv')