Development of a directed graph component

[tiffon]

High level

I'm breaking this down into chunks by targeting the develop-directed-graph branch instead of master.

The repo has been reorganized to use Lerna with the main Jaeger UI app moved into packages/jaeger-ui and the directed graph is being developed in packages/plexus. Lerna is being used to make consumption of the component in Jaeger UI easier during development. The component is being broken out into it's own NPM package because it will be used in other projects, as well.

"plexus"

1. A network or interwoven mass, especially (anatomy) of nerves, blood vessels, or lymphatic vessels.

2. (mathematics) The system of equations required for the complete expression of the relations which exist between a set of quantities.

Wiktionary - plexus

Component

The directed graph will be used in:

• Service dependency graphs
• Viewing a trace as a DAG
• Comparing two traces via comparing two DAGs

This PR implements the functionality to generate the layout (positions and edges) of a graph, but does not have the presentation functionality (React component), yet.

Trying to move briskly due to time constraints, so comments are very light and unit tests are TODO. I wanted to get some eyes on this while moving onto the presentation layer.

[tiffon]

@simonrobb Can you look this over when you get the chance?

[yurishkuro]

so comments are very light and unit tests are TODO. I wanted to get some eyes on this while moving onto the presentation layer.

Could you please separate the lerna-related refactoring into a separate PR and land it?

[tiffon]

@yurishkuro See #209.

[tiffon]

cc @whistlinwilly

[codecov]

Codecov Report

Merging #208 into develop-directed-graph will increase coverage by 0.04%.
The diff coverage is n/a.

@@                    Coverage Diff                     @@
##           develop-directed-graph     #208      +/-   ##
==========================================================
+ Coverage                   89.13%   89.17%   +0.04%     
==========================================================
  Files                         104      104              
  Lines                        2291     2291              
  Branches                      466      466              
==========================================================
+ Hits                         2042     2043       +1     
+ Misses                        210      209       -1     
  Partials                       39       39

Impacted Files	Coverage Δ
...nents/TracePage/TraceTimelineViewer/TimelineRow.js	100% <ø> (ø)
...aceTimelineViewer/SpanDetail/AccordianKeyValues.js	100% <ø> (ø)
...nts/TracePage/TraceTimelineViewer/SpanDetailRow.js	100% <ø> (ø)
...i/src/components/TracePage/SpanGraph/TickLabels.js	100% <ø> (ø)
packages/jaeger-ui/src/selectors/dependencies.js	100% <ø> (ø)
...c/components/TracePage/TraceTimelineViewer/duck.js	100% <ø> (ø)
packages/jaeger-ui/src/utils/configure-store.js	100% <ø> (ø)
packages/jaeger-ui/src/components/App/index.js	100% <ø> (ø)
packages/jaeger-ui/src/utils/sort.js	100% <ø> (ø)
packages/jaeger-ui/src/constants/index.js	100% <ø> (ø)
... and 95 more

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