Since the move to Chi the number of stack frames has proliferated somewhat catastrophically and we're up to 96 frames with multiple tests of the url outside of a trie which is inefficient.
This PR reduces the number of stack frames by 6 through careful use of Route, moves Captcha into its own router so that it only fires on Captcha routes, similarly for avatars and repo-avatars.
The robots.txt, / and apple-touch-icon.png are moved out of requiring Contexter.
It moves access logger higher in the stack frame because there is no reason why it can't be higher.
Extract from #15186
Contains #15292
47fd156936