feat(tutorial): add interactive tutorial with Svelte REPL - #555

Changed pages include:

• index.html - view
• examples.html - view
• getting-started.html - view
• introduction.html - view
• why-svelteplot.html - view
• api/marks.html - view
• api/plot.html - view
• api/transforms.html - view
• examples/area.html - view
• examples/arrow.html - view

There are more changes not included in the list