HTML in BannerGeneral

[taoeffect]

Problem

Prior to @corrideat's fix in PR #2514 for issue #2513, in commit 4e19087, logging in from scratch as user greg results in a "serious error banner" that has HTML inlined to it:

@corrideat fixed the bug causing the banner to appear, but not the bug causing HTML to appear in the banner instead of being rendered.

Solution

Fix it so that HTML is rendered in the BannerGeneral (e.g. using v-safe-html or whatever).

[corrideat]

I don't think my PR has anything to do with this, other than it triggered a serious banner error. Bisection identified this as a regression introduced in #2139.

[SebinSong]

@taoeffect @corrideat I can take care of this issue next week.