rewrite: escape file matcher paths before rewriting (#7683)

* fix: escape file matcher paths in rewrites

Preserve matched file paths containing literal '?' or '%' when try_files rewrites to http.matchers.file.relative.

* test: cover nested escaped try_files rewrite paths

* test: cover encoded slash try_files rewrite paths

* fix: assert file matcher placeholder as string

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Co-authored-by: cyphercodes <cyphercodes@users.noreply.github.com>