Insertion tool needs to respect updateRevisions.txt

The insertion tool right now (I believe) won't respond to updateRevisions.txt files, since it does the commit via libgit2sharp which won't do the commit hooks. This is bad, because it means we won't update revision.txt files that we need to do in some cases, like assembly version changes.

We could fix this in two ways:

1. Shell out to git commit which will run the hooks.
2. Shell out to the hook directly.
2. Reimplement the support in the insertion tool.

Locate the insertion tool and its libgit2sharp commit path, then inspect how updateRevisions.txt, revision.txt, and commit hooks are handled. Reproduce an insertion that should update revision.txt and compare the result with a hook-enabled Git commit; done means the required revision updates occur reliably.

Written by the indexing model from the issue text.