Add dolly camera controls

PR Checklist

Please check if your PR fulfills the following requirements:

[ ] Tests for the changes have been added (for bug fixes / features)
[x] Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[x] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[ ] Other... Please describe:

What is the current behavior?

There's no way to dolly the camera other than mouse scroll wheel

What is the new behavior?

There's camera control methods to dolly in and out

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

The mouse scroll wheel dolly's the camera towards the mouse position. Doing this in combination with zoom can leave the graph in a weird state because dolly has min and max values while zoom does not (e.g. zoom very far in, then you can only dolly back out with the scroll wheel a limited amount. It's not clear these are 2 different methods)

This adds dolly methods to the camera controls that are more comfortable to use in combination with the mouse scroll wheel

https://github.com/reaviz/reagraph/assets/40581813/9f194602-390c-4818-b6a2-bedd98b37450

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reaviz / reagraph