Add some diff functionality to trudag

Objective

Closes #280

This MR adds a new cli to trudag manage (and moves manage lint --diff to come under new cli options)

CLI:

trudag manage diff lint --git-rev BRANCH
trudag manage diff lint --reports LINT_REPORT_1 LINT_REPORT_2

This new option compares json files exported in trudag lint --dump. The idea is a to allow users to track unreviewed items and links between different instances in time.

Next option is:

trudag manage diff graph --git-rev BRANCH

This option does a graph comparison between your current graph specified in the dot file and the graph specified at BRANCH.

Currently the function logs items that have been removed/added. Then if any items have been changed it logs the contents of those items. It also logs if any of the items that have changed include SME scores (useful feature as a Trustable reviewer)

Software Review

• Achieves the stated objective of the change
• Actually addresses linked issue(s)
• Where applicable, changes to trustable directory meet Software Reviewer conditions

Trustable/Safety Review

• Achieves the stated objective of the change
• Actually addresses linked issue(s)
• Where applicable, changes to trustable directory meet Trustable Reviewer conditions

Commit History Review

• Included commits only relate to this MR
• Commit messages are well-formatted and clearly describe changes, Please see guide