Replace TemporaryPublicAccountsBanner with a permanent solution

[Stephen-ONeil]

TemporaryPublicAccountsBanner is necessary to alert users to incomplete actual FTE data on relevant non-infographic routes. Something similar is potentially necessary for planning information at DP time.

Currently, it is an ad-hoc use of the core/NavComponents.js HeaderBanner component and centrally inserted in to the StandardRouteContainer component. That's hacky itself, and it also duplicates (and differs slightly) from the content of the government level infographic "warning panel" on the same topic.

Potential TODOs:

• less hacky way to do this sort of temporary header banners, maybe as special footnotes tagged with relevant route names, make checking for and rendering them part of the StandardRouteContainer responsibilities?
• de-duplicate content between TemporaryPublicAccountsBanner and the relevant late resource footnotes
• make automatic for both PA late FTEs and late DP resources
• consider using the pinned content wrapper on header banners (but only if it looks decent in practice/isn't too onerous)