Move pull and push states from SyncSitesProvider to a new Redux slice

[gcsecsey]

Related issues

Fixes STU-711

Proposed Changes

• Remove pullStates and pushStates React state from SyncSitesProvider
• Implement syncOperations Redux slice

Testing Instructions

• Run npm start
• Go to the Sync tab
• Connect a site
• Pull changes from the site and check that there are no regressions
• Push changes to the site and check that there are no regressions

Pre-merge Checklist

• Have you checked for TypeScript, React or other console errors?

[github-actions]

📊 Performance Test Results

Comparing 7f8a9bb vs trunk

site-editor

Metric	trunk	7f8a9bb	Diff	Change
load	15854.00 ms	16703.00 ms	+849.00 ms	🔴 5.4%

site-startup

Metric	trunk	7f8a9bb	Diff	Change
siteCreation	22219.00 ms	22199.00 ms	-20.00 ms	🟢 -0.1%
siteStartup	6945.00 ms	9029.00 ms	+2084.00 ms	🔴 30.0%

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Results are median values from multiple test runs.

Legend: 🟢 Improvement (faster) | 🔴 Regression (slower) | ⚪ No change