Improve branch cutting script for new branch creation

The current branch cutting script is an AWK script that makes a bunch of assumptions that often require additional tuning from the releng team to make work every time we perform branch cutting.

Rather than using an AWK script that does not understand the structure of YAML we should develop more specialized tools to handle YAML updates in a smarter fashion to minimize the amount of things that need to be tuned after the branch cutting script is complete.

We can use something like the python yaml libraries to handle this and "prettier" to auto-format the YAML files in the releng/builder repo.