replace unnecessary jQuery with vanilla JavaScript

[cjyetman]

There are a sprinkling of jQuery specific commands that could easily be replaced with vanilla JavaScript, reducing/eliminating the dependency on jQuery, e.g.

https://github.com/search?q=repo%3ARMI-PACTA%2Fpacta.portfolio.report+%24.&type=code

For example, this...

pacta.portfolio.report/inst/js/techexposure.js

Lines 402 to 404 in f83c29e

	$.each(legend_data, function(index,item) {
	legend_data[index]["sector_shift"] = unique_sectors.indexOf(item.ald_sector_translation);
	})

could be replaced by...

legend_data.forEach((item) => { item["sector_shift"] = unique_sectors.indexOf(item.ald_sector_translation) });

as was done in RMI-PACTA/pacta.interactive.plot#49