fix: DEV-1904: Fixed source storage duplicating tasks when double click Sync button

[guilhermemachado26]

Description of the proposed changes

Users are being able to click sync button as many times as they want.

In order to avoid running multiple sync jobs at the same time, as a first approach, we have decided to implement a method which checks if there is a sync job already in the queue for that specific project before start the sync.

Jira Ticket

https://heartex.atlassian.net/browse/DEV-1904

[swarmia[bot]]

✅  Linked to Bug DEV-1904 · Source storage duplicated tasks when double click Sync button
➡️  Part of Epic DEV-3239 · Customer Issues - Q3 Sprint 4

[codecov[bot]]

Codecov Report

Base: 77.42% // Head: 77.36% // Decreases project coverage by -0.06% :warning:

Coverage data is based on head (158b878) compared to base (572d0e7). Patch has no changes to coverable lines.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #2915      +/-   ##
===========================================
- Coverage    77.42%   77.36%   -0.07%     
===========================================
  Files          146      146              
  Lines        10775    10791      +16     
===========================================
+ Hits          8343     8348       +5     
- Misses        2432     2443      +11     

Impacted Files	Coverage Δ
label_studio/label_studio/core/redis.py	42.10% <0.00%> (-1.84%)	:arrow_down:
...bel_studio/label_studio/io_storages/base_models.py	79.41% <0.00%> (-1.40%)	:arrow_down:

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[makseq]

I would add simple test here where sync is called twice.