Draft: Add indexing pausing queue

What does this MR do and why?

This is broken into two parts:

1. Add pausing service: !116040 (closed)
2. Handle paused items in indexing queue 👈 (this MR)

Screenshots or screen recordings

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How to set up and validate locally

1. Pause indexing for the NoteIndex

   Search::IndexingPausingService.new.pause!(index_type: Search::NoteIndex)

2. Add an item to processing queue

   Elastic::ProcessBookkeepingService.track!(Note.first)

3. Check queued items for indexing

   pry(main)> Elastic::ProcessBookkeepingService.queued_items
   => {1=>[["Note 1 note_1 project_1", 22.0]]}

4. Check paused queued items

   pry(main)> Search::PausedBookkeepingService.queued_items
   => {}

5. Execute process bookkeeping. It will move paused items to paused queue

   Elastic::ProcessBookkeepingService.new.execute

6. Check queued items for indexing

   pry(main)> Elastic::ProcessBookkeepingService.queued_items
   => {}

7. Check paused queued items

   pry(main)> Search::PausedBookkeepingService.queued_items
   => {1=>[["Note 1 note_1 project_1", 1.0]]}

8. Unpause pause queue

   Search::PausedBookkeepingService.unpause!

9. Check paused queued items

   pry(main)> Search::PausedBookkeepingService.queued_items
   => {}

10. Check queued items for indexing

    pry(main)> Elastic::ProcessBookkeepingService.queued_items
    => {1=>[["Note 1 note_1 project_1", 22.0]]}

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.