Fix multiple ggplotly() regressions

[cpsievert]

This PR fixes 7 ggplotly() bugs, primarily related to legend handling, theme translation, and tooltip generation:

• ggplot() does not display aesthetic in tooltip when aesthetic name == 'group' #2415: Variable named 'group' now shown in tooltip when mapped to aesthetic (e.g., colour = group)
• Since ggplot2 4.0.0, theme_bw() looks like theme_minimal() #2455/panel.border() is ignored inside ggplotly() #2460: element_blank panel.border no longer creates empty shapes (ggplot2 4.0.0 compatibility)
• Unused aesthetic in scale_*_manual causes ggplotly conversion to fail #2466: scale_*_manual with unused aesthetics no longer errors (e.g., aesthetics = c("colour", "fill") when only colour is used)
• Boxplot outliers not removed. #2305: geom_boxplot(outlier.shape = NA) now hides outlier points
• Use of multiple aesthetics in scale_*_manual causes legend to be dropped in ggplotly conversion #2467: Multi-aesthetic scales now show legend and split traces correctly
• Legend position not preserved when converting ggplot2 to plotly #2407/ggplotly doesn't respect legend.position from theme() #2187: legend.position theme element now translated to plotly layout (bottom, top, left, inside/numeric)
• ggplotly drops legend if geom_blank is used #2281: geom_blank() no longer drops legend for other geoms in the same plot

Closes #2415
Closes #2455
Closes #2460
Closes #2466
Closes #2305
Closes #2467
Closes #2407
Closes #2187
Closes #2281

Test plan

• Added tests for each fix in the appropriate test files
• All new tests pass
• Existing tests continue to pass

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