cdf-cli: `packages init` command

[janaka]

cdf-cli packages init <name> --language=<lang> --runtime=<awscdk | cdktf > --cicd=<github>

Generates scaffolding for a package from a template. Initially we'll only support TypeScript. Includes custom module template files and build and deploy config (only actions supported initially). Template TBD (probably base off the sample package with some adjustments).

note: cdf-cli is the name of the executable.