Add Makefiles to streamline development

[techouse]

Since dart CLI commands can be cumbersome I wrote a few Makefiles to make stuff easier 😇

To inspect each of their targets simply run

make help

and you'll be greeted by a list of options, e.g.

cd chopper
make help

will print

Target               Description
------               -----------
analyze              Analyze the project's Dart code.
check_format         Check the formatting of one or more Dart files.
check_outdated       Check which of the project's packages are outdated.
check_style          Analyze the project's Dart code and check the formatting one or more Dart files.
code_gen             Run the build system for Dart code generation and modular compilation.
code_gen_watcher     Run the build system for Dart code generation and modular compilation as a watcher.
format               Format one or more Dart files.
install              Install all the project's packages
show_test_coverage   Run Dart unit tests for the current project and show the coverage.
sure                 Analyze the project's Dart code, check the formatting one or more Dart files and run unit tests for the current project.
tests                Run Dart unit and widget tests for the current project.
upgrade              Upgrade all the project's packages.

All of these will run fine on macOS and Linux, not sure about Windows 🙈

[techouse]

Looks like upgrading code_builder to 4.3.0 in the unit tests triggered another deprecation warning. 🚨

I wonder if we should include the pubspec.lock to avoid these scenarios.

@JEuler / @stewemetal your thoughts?

[techouse]

This needs #358 to pass the tests.

[techouse]

All tests pass 🚀