[aliases] Do not replace existing aliases

[Nuru]

what

1. [aliases] Do not overwrite existing commands with our default aliases and functions
2. [codefresh] Add some helper functions to be used with Codefresh CI/CD pipeline
3. [tfenv] Set a default TFENV_BLACKLIST if the variable is not already one set
4. [docker] Tag docker images with short commit tags as well as long ones

why

1. If a user has customized Geodesic in a way that conflicts with our defaults, let the user's customization win. Better user experience.
2. Move toward using Geodesic rather than Build Harness inside CI/CD pipelines.
3. Prevent secrets in the environment from leaking into Terraform.
4. Short tags are easier for humans to deal with, and are more visible in the GitHub UI.

[osterman]

I think this should be generalized to config-directory and take an argument which is the project (e.g Helmfile)

[Nuru]

Replaced with conf-directory helmfiles