Allow resizing deepscatter canvas

[bmschmidt]

This PR starts implementing resizing a deepscatter plot by calling plot.resize(width, height).

• [x] resize all WebGL buffers
• [x] resize all DOM elements
• [x] adjust bbox of d3.zoom
• [ ] ensure scale, get_current_corners() understand the new bbox
• [ ] maintain center of viewport on resize, not upper-left.
• [ ] Don't drop background color

[bmschmidt]

• #81 👈 (View in Graphite)
• #194 : 1 other dependent PR (#192 )
• main

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[RLesser]

Is this ready @bmschmidt ? would be nice to have