- Fix relative imports not working
- Update dependencies (codeBuilder, source_gen)

I personally spent a couple hours trying to figure out why the example code was not working for me and it turned out to be a combination of things:

The `asExtension` parameter should be true (Which is now the default) and I was not importing the generated code. Both of these have been previous topics of discussion on SO and the repo, so it made sense address them to prevent further confusion.

* https://stackoverflow.com/questions/63370674/the-function-initgetit-isnt-defined-while-using-injectable-pub-package/63668392#63668392
* https://github.com/Milad-Akarie/injectable/issues/326

 Add support for micro package modules scopes

Add support for external package modules
Add support for GetIt scopes
Add @PostConstruct annotation to execute sync/async code after construction
Add preResolve to @FactoryMethod annotation
Add throwOnMissingDependencies flag to @InjectableInit annotation
Change asExtension default value to true [breaking change]
Change initializerName default value to 'init' [breaking change]

Add support for external package modules
Add support for GetIt scopes
Add @PostConstruct annotation to execute sync/async code after construction
Add preResolve to @FactoryMethod annotation
Add throwOnMissingDependencies flag to @InjectableInit annotation
Change asExtension default value to true [breaking change]
Change initializerName default value to 'init' [breaking change]

get_It -> get_it

Signed-off-by: ainus <dev@ainus.co.kr>

Pomp up versions of build_runner -> 2.0.1, code_builder -> 4.0.0, analyzer -> 1.5.0
Add buymecoffee badge to README.md

Fix named instances are ignored when sorting dependencies.
Clean up some code
add resolver test cases

change min version constraint of GetIt to 5.0.0
update readme file

- get_it package name is fixed

Add option to generate the initilizer function as an extension
Change initializer functions returns the passed get_it instance instead of void
Add Advanced environment filter that can be extended and customized
Fix Injectable generator not handling multiple instances of generic types #107

Add option to not prefer relative imports in @InjectableInit

Add generation-time check for duplicate dependencies under the same environment
Fix 3rd party imports from src instead of library file issue
Change generated file extension to .config.dart
Change generated file applies to most of effective dart rules including preferring relative imports
Clean up some code

Add generation-time check for duplicate dependencies under the same environment
Fix 3rd party imports from src instead of library file issue
Change generated file extension to .config.dart
Change generated file applies to most of effective dart rules including preferring relative imports
Clean up some code

Add some comments

fix generic types are registered as dynamic
fix unresolved future when registering asynchronous dependencies
change asynchronous dependencies will be registered using async factory unless annotated with @preResolve

fix src import issue

- add support for custom initializers in register Modules
- minor fixes