Add some missing Unity library files

.gitignore

Library/AnnotationManager

Library/BuildPlayer.prefs

Library/BuildSettings.asset

Library/EditorUserBuildSettings.asset

Library/EditorUserSettings.asset

Library/InspectorExpandedItems.asset

Library/LastSceneManagerSetup.txt

Library/LibraryFormatVersion.txt

Library/MonoManager.asset

Library/ProjectSettings.asset