PSAvoidUsingConvertToSecureStringWithPlainText makes unreasonable claims at high severity

Internal MS situation:

PSAvoidUsingConvertToSecureStringWithPlainText is now generating SFI/s360 work based on unsupported claims with neither Guardian nor TSA teams able to offer repo-wide suppression options.

This will expose secure information. Encrypted standard strings should be used instead.

Will it? Why is it an error?
I challenge you to create Credential instance from a token or another credential following this guidance.

There are workarounds of course and line-by-line suppressions, but they don't scale or make security story any stronger and we can't provide our own rules/settings for the linter.

首先定位 PSAvoidUsingConvertToSecureStringWithPlainText 规则的入口点，并检查其消息和严重性是如何定义的。将这些说法与 issue 中描述的凭据和令牌场景进行比较；完成的标准是，该规则的严重性和指导不再对整个仓库提出无依据的安全性主张。