add percent change to timeseries tooltip (#42059)

* add percent change to timeseries tooltip

* move computeChange to lib/numeric

* cleaning up code in numeric.js

* color text

* add unit to key

* move change to tooltip footer

* fix extra bottom spacing

* remove color

* handle gaps in data

* clean up code

* add change to funnel tooltip

* move retained to footer in funnel

* update copy

* remove min decimal count

* rename events.tsx -> events.ts

* add test cases to line-bar-tooltips.cy.spec.js

* add specs for edge cases

* readd exports to fix numeric.unit.spec.js

* don't show for change for scatterplot

* translate retained

* use parseTimestamp instead of String

* handle quarter interval

* remove redundant dayjs calls

* handle quarter with Feburary correctly