Update php-cs-fixer and cleanup codebase

.docheader

.gitignore

.php-cs-fixer.dist.php

.php_cs.dist

composer.json

features/bootstrap/FeatureContext.php

src/Avro/Loader/ChainLoader.php

src/Avro/Loader/DirectoryLoader.php

src/Avro/Loader/FileLoader.php

src/Avro/Loader/Loader.php

src/Avro/Loader/LoaderError.php

src/Avro/Transpiling/ClassName.php

src/Avro/Transpiling/Class_.php

src/Avro/Transpiling/DTO.php

src/Avro/Transpiling/Enum.php

src/Avro/Transpiling/HasTranspiler.php

src/Avro/Transpiling/Namespace_.php

src/Avro/Transpiling/Package.php

src/Avro/Transpiling/Property.php

src/Avro/Transpiling/PropertyLogicalType.php