Fix EZP-23337: New stack does not generate 301 redirects for wrongly cased URLs

This PR revolves issue https://jira.ez.no/browse/EZP-23337

Case correction redirection was not implemented.

This implements it, with one improvement over Legacy Stack behaviour. In LS, for custom resource alias (e.g. custom alias on `/content/search` resource), case-incorrect URL would result in the redirection to the resource itself, rather than to the case-corrected custom alias. That seems incorrect, and behaviour here is therefore redirection to the case-corrected custom alias.

Note: forward (redirect) flag has precedence, so requesting case-incorrect URL for the forwarding custom alias will not result in redirection to the case-correct alias but to the original resource directly.

Tests: unit tests + manual integration testing.
That would mean case-correction will happen even for forwarding custom alias and we should not do that. I added a new test case in https://github.com/ezsystems/ezpublish-kernel/commit/ee65aec20769b869efc1832fc1896641e0284aa4, what do you think?