feat(singleton): singleton pattern implementation on container class

feat(singleton): support for set a singleton from an object

feat: support for optional constructor parameters

docs(readme): fix usage in flight apps invalid php 7.4 example

docs(readme): fix uses in examples

fix(composer.json): support for php 8

docs(readme): add badges

chore(.gitattributes): add .gitattributes

docs(readme): add readme

Initial commit