Refactor the various relationship details views into one shared bit of code

[stevenday]

So That

• I have a single unit of code which provides all relationship diagrams, not several competing versions which confuse me.
• I can ensure I’m presenting a consistent experience to the user whenever I use a tooltip.
• I can test one piece of code and be confident it handles all of the eventualities of relationship display.

A/C

• The relationships on this page: https://register.openownership.org/entities/59bfef8b67e4ebf3402d021b/59bfef7767e4ebf3402cedb1-unknown are produced by the same partial view and styled by the same CSS as the relationships on a tooltip on this page: https://register.openownership.org/entities/59bfef8b67e4ebf3402d021b/graph.
• The two views look visually consistent, barring necessary differences for the varying contexts they’re displayed in.
• There’s a test suite for that partial view which tests all of the ways it can be used to display relationships.