[Nest][Feature] - Re-write Git patch scripts in Dart

[matthew-carroll]

Nest has a couple scripts that import and export changes as patch files. This is a critical part of contributing changes to Flock, as well as creating the latest Flock version on top of Flutter.

These scripts are currently written in Python.

We should rewrite these scripts in Dart for the following reasons:

• Our maintainers are much more familiar with Dart than Python.
• Dart provides compile-time safety.
• Dart with data structures provides IDE hints for more effective development.
• The above points make it easier for us to identify errors during code execution and report them in human readable ways during execution. The biggest concern with these scripts isn't about when they're successful. The challenge is root causing issues when they fail. That will be easier for us in Dart.