RFC for pluggable logging model

Per #106, this is to track the need for an RFC that would create a pluggable provider model for logging. Quoting me from that thread:

@PowerShell/powershell-committee discussed this one in detail today. We believe that there's massive value in figuring out how to tee logs off to remote logging providers, but a bunch of the semantics in this RFC are specific to Splunk.

Instead, we think an RFC should be authored that builds a provider/plugin model for allowing multiple remote logging providers. This RFC should also give consideration to whether local logging targets should be treated the same way (e.g. if you want to exclusively log to a remote target, maybe in serverless/stateless scenarios). There should also be a consideration of whether we should have something like a Get-PSLog or Write-PSLog that are agnostic to logging providers.

The PowerShell Team has a strong interest in picking this up, but we have no idea when we can get to it right now. We only know that it should be a flexible, pluggable model.

先阅读 issue #106 以及此处引用的 PowerShell Committee 讨论，以了解现有的 Splunk 特定语义。起草一份 RFC，定义灵活的 provider/plugin 模型，包括远程和本地目标以及与 provider 无关的日志记录操作；当所提议的模型涵盖这些场景并准备好接受社区反馈时，即视为完成。