Added an option to live grep through files in quickfix list

[schrc3b6]

Description

It is currently not possible to live grep through files in my quickfix list.
It is possible to filter through the quickfix list results with builtin.quickfix or Cfilter,
but not to grep through the files in the quick fix list.

I often want to see files that contain multiple keywords.
My current workflow is to telescope live grep for the first keyword. If I then see that I need to further limit the search, I save the results to the quickfix list. Close all buffers except those on my quickfix list and live grep through all open buffers.
Closing all other buffers is however tedious, especially if I need them afterward.

Therefor, option to search only the buffers on the quickfix list would be nice :)

Type of change

• New feature (non-breaking change which adds functionality)
• This change requires a documentation update

How Has This Been Tested?

Tested with neovim version v0.10.2 on Arch

• with empty quickfix list -> regular live grep
• with quickfix list with invalid paths
• with valid quickfix list

Checklist:

• My code follows the style guidelines of this project (stylua)
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (lua annotations)
• I followed the style of grep_open_files