[Bug] Ensure updates to state are done atomically in ConfigurationManager

[keegan-caruso]

Which version of Microsoft.IdentityModel are you using?
Note that to get help, you need to run the latest version.
Microsoft.IdentityModel 8.5.0

Where is the issue?

• M.IM.JsonWebTokens
• M.IM.KeyVaultExtensions
• M.IM.Logging
• M.IM.ManagedKeyVaultSecurityKey
• M.IM.Protocols
• M.IM.Protocols.OpenIdConnect
• M.IM.Protocols.SignedHttpRequest
• M.IM.Protocols.WsFederation
• M.IM.TestExtensions
• M.IM.Tokens
• M.IM.Tokens.Saml
• M.IM.Validators
• M.IM.Xml
• S.IM.Tokens.Jwt
• Other (please describe)

Expected behavior

Ensure updates to state are done atomically in ConfigurationManager.

See #3090, these changes showed a viable way to handle this. It would need small changes to work with 8.5.0

Actual behavior

_syncAfter and _lastRequestRefresh do not have guaranteed atomic updates.