Feat: refactor deptree generation

[justshiv]

• [x] Ready for review
• [x] Follows CONTRIBUTING rules
• [ ] Reviewed by Snyk internal team

DONE:

• [x] Adds methods to generate flat collection of dependencies, find those that occur too frequently and print those out in meta-common-packages tree.

TODO:

• [x] Hook up existing full tree print to use the done methodology

• [x] Refactor use of types as I am being a bit verbose at the moment

[snyksec]

:tada: This PR is included in version 1.4.0 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot :package::rocket: