Port "C#: Set proxy environment variables, if Dependabot proxy is detected" to 2.20.0 release branch#18238

mbg merged 15 commits intocodeql-cli-2.20.0github/codeql:codeql-cli-2.20.0from

mbg/csharp/codeql-cli-2.20.0/set-proxy-cert-filegithub/codeql:mbg/csharp/codeql-cli-2.20.0/set-proxy-cert-fileCopy head branch name to clipboard