Deferred Log Dispatcher

[RohitRanjanMS]

The initial telemetry from the host startup is missing in Application Insights because the ApplicationInsightsLoggerProvider is added later in the process. As a result, important startup logs are not captured in App Insights. The proposed solution addresses this by temporarily storing logs in a channel and forwarding them to Application Insights and/or OpenTelemetry once these providers are added to the logging system.

resolves #9679 and #9361

Pull request checklist

IMPORTANT: Currently, changes must be backported to the in-proc branch to be included in Core Tools and non-Flex deployments.

• Backporting to the in-proc branch is not required
  • Otherwise: Link to backporting PR
• My changes do not require documentation changes
  • Otherwise: Documentation issue linked to PR
• My changes should not be added to the release notes for the next release
  • Otherwise: I've added my notes to release_notes.md
• My changes do not need to be backported to a previous version
  • Otherwise: Backport tracked by issue/PR #issue_or_pr
• My changes do not require diagnostic events changes
  • Otherwise: I have added/updated all related diagnostic events and their documentation (Documentation issue linked to PR)
• I have added all required tests (Unit tests, E2E tests)

[jviau]

Some comments which hopefully remove the need to touch the other loggers.

Also, this approach will not capture log scopes. Is that okay? Or do you want to buffer scope data as well? Just make sure to capture scope data as a string and not their raw types (they may capture async state which we don't want)

[jviau]

ILoggerProvider approach looks good. However, lets worry about capturing and re-emitting scope in a separate PR.

BUT I still recommend using the ISupportExternalScope for the ILoggerProvider and ILogger implementation in this PR.

[fabiocav]

Thank you, @RohitRanjanMS

The new iteration looks good, but I'm still concerned about the placeholder logs question.

Have you validated this functionality in placeholder? I want to make sure warmup site logs won't end up in customer facing Application Insights logs.

Addressed all the comments.