Fix issues #2810, #2813, #2822, #2829

[abraunegg]

• Add isValidUTCDateTime function to validate timestamp as received from OneDrive API to ensure it is valid
• Use new function before attempting to call SysTime.fromISOExtString to ensure this call will be successful
• If there is no timestamp in the JSON, set it to the system time
• Add assertion when building an item from DB data, if this fails with bad timestamp data
• Revert to v2.4.25 sqlite 'synchronous' configuration
• Add new function (isValidUTF8) to check UTF-8 validity of a string before regex check
• In a --resync scenario, if the file hash is the same, use the online timestamp
• Ensure that the session URL data is a valid JSON response before use

These fixes all seem unrelated .. however these are the potential root causes for all the issue tickets:

• Debian | Docker being used, potential root cause old curl version problem (fixed via #2831)
• SQlite 'synchronous' configuration to ensure DB data is written to disk correctly (fixed via #2816)

[abraunegg]

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