Azure.Sdk.Tools.TestProxy_1.0.0-dev.20220808.4

Vendor CrossPlat PemReader from azure-core (#3882)

* standardize line endings for RecordingHandler.cs. Update pem to an expired certificate that should be valid crossplat. remove trial RemoveOnLinuxFact
* use vendored internal-only azure-core classes for loading a X509Certificate2 from the TLS Certificate input string.