fix(job): make job api support env option

.SpaceVim.d/tasks.toml

@@ -1,3 +1,9 @@
+[vader-test]
+    command = "make"
+    args = ['test']
+    isBackground = false
+[vader-test.options.env]
+    VIM_BIN = 'nvim'
 [generate-vim-doc]
     command = "python"
     args = ['-m', 'vimdoc', '.']

autoload/SpaceVim/api/job.vim

@@ -159,6 +159,9 @@ function! s:self.warp_nvim(argv, opts) abort dict
   if has_key(a:opts, 'cwd')
     call extend(obj.opts, {'cwd' : a:opts.cwd})
   endif
+  if has_key(a:opts, 'env')
+    call extend(obj.opts, {'env' : a:opts.env})
+  endif
   return obj
 endfunction