feat: DEV-3145: Add command for export project in Opensource

[guilhermemachado26]

Description of the proposed changes

These changes add a new command to export a Label Studio project in a specific format.

label-studio export <project-id> <export-format>

• The file generated will be saved inside settings.EXPORT_DIR folder.
• All the project tasks will be included in the process.
• Default values will be used to flags like INTERPOLATE_KEY_FRAMES and CONVERTER_DOWNLOAD_RESOURCES defined in the settings file.

Jira Ticket

https://heartex.atlassian.net/browse/DEV-3145

[swarmia]

✅  Linked to Story DEV-3145 · Add command for export in opensource
➡️  Part of Epic DEV-2854 · Export issues - no epic

[codecov]

Codecov Report

Merging #2824 (a4d0b15) into develop (c800f2b) will increase coverage by 0.10%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop    #2824      +/-   ##
===========================================
+ Coverage    77.04%   77.14%   +0.10%     
===========================================
  Files          144      144              
  Lines        10599    10643      +44     
===========================================
+ Hits          8166     8211      +45     
+ Misses        2433     2432       -1     

Impacted Files	Coverage Δ
label_studio/label_studio/server.py	41.63% <0.00%> (-0.90%)	⬇️
label_studio/label_studio/core/utils/common.py	84.29% <0.00%> (-0.27%)	⬇️
label_studio/label_studio/data_export/mixins.py	88.02% <0.00%> (+0.06%)	⬆️
label_studio/label_studio/core/argparser.py	96.72% <0.00%> (+0.42%)	⬆️
label_studio/label_studio/data_export/models.py	91.20% <0.00%> (+10.98%)	⬆️
label_studio/label_studio/tasks/functions.py	66.10% <0.00%> (+27.39%)	⬆️

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[makseq]

@guilhermemachado26
Let's extend documentation:
1 right after this section https://labelstud.io/guide/export.html#Export-timeout-in-Community-Edition (export timeout) - insert your new command
2 in export timeout section please write: "Also you can use a console command for export, (see more below)[link to your new section]

[makseq]

unfortunately this PR breaks LS completely. Tests are broken too.