feat: Open quickfix list on it's own action (#497)

Given that Telescope has a picker for quickfix items, opening its
window automatically isn't that useful, so this commit removes the call
from send_to_qflist and send_selected_to_qflist. Some users may prefer
the old behaviour though so a new action open_qflist was created.

To open quickfix with one key, you can do this:
```
       ["<C-q>"] = actions.send_to_qflist + actions.open_qflist,
```

Co-authored-by: Tae Sandoval <tssm@users.noreply.github.com>

lua/telescope/actions/init.lua

@@ -304,7 +304,6 @@ actions.send_selected_to_qflist = function(prompt_bufnr)
   actions.close(prompt_bufnr)
 
   vim.fn.setqflist(qf_entries, 'r')
-  vim.cmd [[copen]]
 end
 
 actions.send_to_qflist = function(prompt_bufnr)
@@ -319,6 +318,9 @@ actions.send_to_qflist = function(prompt_bufnr)
   actions.close(prompt_bufnr)
 
   vim.fn.setqflist(qf_entries, 'r')
+end
+
+actions.open_qflist = function(_)
   vim.cmd [[copen]]
 end