Issue #3293157 by phenaproxima, tedbow: Make everything internal

package_manager/src/EventSubscriber/UpdateDataSubscriber.php

package_manager/src/ExecutableFinder.php

package_manager/src/FileSyncerFactory.php

package_manager/src/PackageManagerServiceProvider.php

package_manager/src/PackageManagerUninstallValidator.php

package_manager/src/PathExcluder/GitExcluder.php

...ge_manager/src/PathExcluder/SiteConfigurationExcluder.php

package_manager/src/PathExcluder/SiteFilesExcluder.php

package_manager/src/PathExcluder/SqliteDatabaseExcluder.php

package_manager/src/PathExcluder/TestSiteExcluder.php

package_manager/src/PathExcluder/VendorHardeningExcluder.php

package_manager/src/ProcessFactory.php

package_manager/src/ValidationResult.php

...age_manager/src/Validator/ComposerExecutableValidator.php

package_manager/src/Validator/ComposerSettingsValidator.php

package_manager/src/Validator/DiskSpaceValidator.php

package_manager/src/Validator/LockFileValidator.php

package_manager/src/Validator/MultisiteValidator.php

package_manager/src/Validator/PendingUpdatesValidator.php

package_manager/src/Validator/SettingsValidator.php