perfetto-ui: Make panning and zooming snappier
perfetto-ui: Make panning and zooming snappier

This patch adjusts the panning and zooming animations to make them more
responsive, especially when the corresponding key is pressed multiple
times in a row. The algorithm maintains a desired pan/zoom offset and
uses a spring force to incrementally move the viewport toward that
orientation.

Change-Id: I1e2b2b3ffeb1db4a2c1bc3994ecd66b4e146c5c3

google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto