CVE-2021-21645: Missing permission checks in Jenkins Config File Provider Plugin allow enumerating configuration file IDs

The vulnerability stemmed from missing permission checks in HTTP endpoints handling configuration files. The commit diff shows critical methods in ConfigFilesManagement, ManagedFile, Mvn*Providers, and FolderConfigFileAction had their permission checks either added or upgraded from weaker checks (e.g., EXTENDED_READ to ADMINISTER). These functions allowed attackers with read access to enumerate IDs via endpoints that should require higher privileges. The test cases added in Security2203Test explicitly validate() that these methods now enforce proper permissions, confirming their prior vulnerability.