Demo: Write demonstration code for additional attacks for the console demo

[awwad]

Request for New Functionality

The task is to generate a variety of additional attacks in the Uptane demo, based on the Uptane Design Overview and a few TUF [1] [2] and Uptane papers.

• After introducing yourselves to TUF and Uptane, see the list of general attacks Uptane protects against here.
• The current attacks demonstrated in the demo are listed in section 3 of the Uptane GitHub repo's readme.
• Code for the existing attack demonstrations lives in the demo_director and demo_imagerepo modules in the demo directory of the Uptane repo. Examples: mitm_arbitrary_package_attack(), the various *replay_attack_* functions(), sign_with_compromised_keys_attack(), ....

Once you have some functional attacks, add some instructions and explanatory text to README.md.