Workspace menu

[texodus]

• Moves the Row Count component to the individual panels (instead of just the active panel.
• Adds a new "Workspace" dropdown menu where the row count component used to be, which has sections for creating from a Table or duplicating a Panel.
• Cleaned up SVG icons:
  • The "Y Scatter", "Candlestick", "OHLC", "Treemap" and "Sunburst" plugin icons have been updated to be less abstract.
  • The column selector checkbox has been de-emphasized and made to look more like a checkbox.
  • The theme selector icon has been replaced.
  • The column type icons have been enlarged (slightly), aligned and generally made easier to read.

Drive-by fixes

• Fixes Plugin packages declare empty version ranges for @perspective-dev/client / @perspective-dev/viewer, allowing mixed-version installs #3222
• Fixes perspective-python Segfault when visible number of row quickly change #3103, upgrades pyo3