feat(discover): enable multi y axis for previous period view

[edwardgou-sentry]

Adds multi y axis support for Previous Period display view in Discover results chart:

When using multiple y axis series, previous period series will be plotted as stacked dotted lines using colours based off the original series. Single y axis previous period display is unchanged (will still use grey when plotting previous period series).

currentSeriesName and previousSeriesName props in EventsRequest were pluralized and changed from string type to string[] to support multiple previous series. Some dependants of EventsRequest were updated to reflect this but without any functional changes.

[github-actions]

size-limit report

Path	Base Size (284fefe)	Current Size	Change
src/sentry/static/sentry/dist/entrypoints/app.js	52.66 KB	52.67 KB	+0.02% 🔺
src/sentry/static/sentry/dist/entrypoints/sentry.css	70.89 KB	70.9 KB	+0.03% 🔺

[edwardgou-sentry]

size-limit report

Path Base Size (493559e) Current Size Change
src/sentry/static/sentry/dist/entrypoints/app.js 52.51 KB 52.51 KB -0.02% 🔽
src/sentry/static/sentry/dist/entrypoints/sentry.css 70.89 KB 70.89 KB 0%

Is this a false alarm?

[scttcper]

Is this a false alarm?

I think baseChart is in the main bundle

[wmak]

Mostly looks good to me, but I think this might have broken previous period legends on single axis

And isn't formatting equations properly when multi-axis is enabled:

[edwardgou-sentry]

@wmak 👍 nice catch, fixed!

[wmak]

LGTM