Make updates to syncAfter and lastRefreshRequest atomic

[keegan-caruso]

Make updates to syncAfter and lastRefreshRequest atomic

Description

syncAfter can be updated on a background thread,
lastRefreshRequest could be simultaneously updated
by different threads as there is not a lock around
the check and update.

To be able to do an atomic write, DateTimeOffset fields had
to be switched to DateTime fields. DateTime is a struct
with a single ulong field, DateTimeOffset has two fields,
one for the datetime, one for the offset. DateTime can
be treated as a long for this reason (and is in DateTime's ToBinary method).

This also means ConfigurationManager can continue to use DateTime instead of an
int, which is much more ergonomic.

See the [implementation] for when you can't use a long and need to use a ulong: https://github.com/dotnet/runtime/blob/main/src/libraries/System.Private.CoreLib/src/System/DateTime.cs#L1316

Fixes #2900

[github-actions]

Summary

Summary

Generated on:	1/12/2025 - 12:51:28 AM
Coverage date:	1/12/2025 - 12:42:06 AM - 1/12/2025 - 12:51:02 AM
Parser:	MultiReport (60x Cobertura)
Assemblies:	1
Classes:	7
Files:	2
Line coverage:	80.3% (620 of 772)
Covered lines:	620
Uncovered lines:	152
Coverable lines:	772
Total lines:	483
Branch coverage:	67.8% (228 of 336)
Covered branches:	228
Total branches:	336
Method coverage:	Feature is only available for sponsors

Coverage

Microsoft.IdentityModel.JsonWebTokens - 80.3%

Name	Line	Branch
Microsoft.IdentityModel.JsonWebTokens	80.3%	67.8%
Microsoft.IdentityModel.JsonWebTokens.JwtTokenUtilities	100%
System.Text.RegularExpressions.Generated	80.3%	67.8%
System.Text.RegularExpressions.Generated	80.3%	67.8%
System.Text.RegularExpressions.Generated.<RegexGenerator_g>F12A1AEDDDFE32BA DF4DBFF323AF1BCB48B9F9721B7CD3E05F5E034CF225E3DF8__CreateJweRegex_1	79.2%	68%
System.Text.RegularExpressions.Generated.<RegexGenerator_g>F12A1AEDDDFE32BA DF4DBFF323AF1BCB48B9F9721B7CD3E05F5E034CF225E3DF8__CreateJwsRegex_0	81.4%	67.6%
System.Text.RegularExpressions.Generated.<RegexGenerator_g>F334844C618E00D3 CEC5D3FE0D00CF0141BBEE98635313BB2CB8D3921464CE05A__CreateJweRegex_1	79.2%	68%
System.Text.RegularExpressions.Generated.<RegexGenerator_g>F334844C618E00D3 CEC5D3FE0D00CF0141BBEE98635313BB2CB8D3921464CE05A__CreateJwsRegex_0	81.4%	67.6%