extend create_project to include .secrets, optional pre-commit to detect secrets

## Is your feature request related to a problem? Please describe.
For some workstreams a key or token may be needed and there is always a risk of individuals pushing keys/tokens to repo's.

## Describe the solution you'd like
Include under create_project a .secrets file (or .env) which is untracked by git / included in the .gitignore as either standard or by optional toggle. Optionally, this could be extended to include a pre-commit hook which searches a repo for token/keys before a commit.

## Describe alternatives you've considered
Users should use environment variables and not push secrets, guidance should assist with this but having it as part of the default project template with a back-up pre-commit hook can help limit this risk.

## Additional context
Similar functionality is provided in the govcookie cutter repo but the pre-commits and structure are a bit buggy for R as this was mainly python focused originally: https://github.com/best-practice-and-impact/govcookiecutter