[Table] Add a way to highlight selected row

[kiaking]

When making table selectable, it would be cool if we can highlight that row. Not sure how API should look like.

I think the bg color should be set to --c-bg-mute-1 in order to distinguish from hover style. But maybe it makes texts harder to read... so --c-bg-elv-4 could be enough 🤔

[brc-dd]

hover has --c-bg-elv-4 -- it'd be same for both then 👀

sefirot/lib/components/STableCell.vue

Lines 134 to 135 in ad21b8c

	.row:hover & {
	background-color: var(--c-bg-elv-4);

[kiaking]

@brc-dd
Yeah it would. So, the down side is user will not notice the change until they remove the mouse from that row after selecting it 👀 But... I think it would be noticeable enough. I hope 🙏