Make graph prettier with node glyphs

[epage]

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Context

We can clarify and include some commit / branch status in the tree itself, like git-branchless

For glyph ideas, see https://github.com/arxanas/git-branchless/blob/master/src/core/formatting.rs#L143

[epage]

For example

• Vertical ellipses would be nice for omitted commits
• We could use x for WIP / fixups
• We could use the arrow for HEAD