[clean-up]: Remove deprecated plexus/DirectedGraph

[hari45678]

Which problem is this PR solving?

• Resolves Remove deprecated plexus/DirectedGraph #1940

Description of the changes

• This PR removes the DirectedGraph component from plexus lib. The component was anyway looking ugly on demos (big arrows), which might be due to the fact that it stopped receiving changes.

How was this change tested?

• npm run start in plexus package.

Checklist

• I have read /~https://github.com/jaegertracing/jaeger/blob/master/CONTRIBUTING_GUIDELINES.md
• I have signed all commits
• I have added unit tests for the new functionality
• I have run lint and test steps successfully
  • for jaeger: make lint test
  • for jaeger-ui: npm run lint and npm run test

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.63%. Comparing base (355758b) to head (d45e161).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2548   +/-   ##
=======================================
  Coverage   96.63%   96.63%           
=======================================
  Files         255      255           
  Lines        7728     7728           
  Branches     1950     1950           
=======================================
  Hits         7468     7468           
  Misses        260      260           

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[hari45678]

A new version of plexus can also be published to npmjs

Steps:

• Change the version in plexus/package.json to 0.3.0 (for a minor up).
• run npm run build
• npm login
• npm publish
• done

[hari45678]

I have changed the demos to align with Digraph props and types.

[yurishkuro]

Thanks!