Add session and code attribution for plots

[jmcphers]

This change adds a number of quality-of-life improvements to the Plots pane.

Session attribution

The Plots pane now has an indicator showing which session a plot was emitted from:

Clicking on this indicator will take you to the session's console, at the point in history where the plot was generated if possible.

Addresses #7031.

Code attribution

There is a new toolbar button containing actions dealing with the code used to generate the plot. This makes it easy to draw the plot again with new data, to refine the plot command, or to get context around the original plot command.

Note

The "code used to generate the plot" is considered to be the "the statement that was being executed when the plot appeared". Complicated plots are sometimes built over multiple statements, and capturing the exact set of statements used to generate a plot is not possible without a lot of semantic analysis and guesswork. We may invest in this in the future if it looks like it will be helpful.

Addresses #10183.

Plot naming

Each plot now has a unique name sent from the backend. These names can help distinguish plots that otherwise look similar in thumbnail views, and also provide more meaningful default titles when navigating, opening in editor tabs, or saving/exporting.

Filmstrip accessibility

The history filmstrip is now a lot more accessible.

• History thumbnails are now <button> elements and also use the default focus outline decoration when focused
• Less precision is required when clicking; the click target and selection outline is now always a large square, instead of wrapping around just the plot.
• More keyboard navigation commands for the thumbnails have been added, including vi-like navigation and Del to delete a plot
• The close button now has better theme colors and good contrast in both light and dark themes
• Scrolling aggression has been turned down so that selecting a plot only scrolls enough for that plot to come into view (instead of scrolling the whole filmstrip)

Addresses #3651.

Requires posit-dev/ark#998.

Release Notes

New Features

• The Plots pane now shows which session created the plot (Plots: Provide session attribution or filtering #7031)
• The Plots pane can now navigate to, copy, or re-run the code used to create a plot (Plots: Show/link to code used to generate plot #10183)

Bug Fixes

• Fixed poor contrast ratio in the Close button in the Plot history (Close plot button hard to see X with dark themes #3651)

QA Notes

Test tags: @:plots

[github-actions]

E2E Tests 🚀
This PR will run tests tagged with: @:critical @:plots

^{readme  valid tags}

[jmcphers]

The remaining test failures appear to be happening because the baseline images for the tests need to be updated to use slightly different offsets.