Case insensitive URLs for library detail

[gavinwahl]

Redirect to the canonical case when it does not match. This adds a case-insensitive unique constraint on library slugs to make this safe.

Fixes #163

[sdarwin]

If this works correctly, then ok by me. After merging to staging, there is a chance to test further if there is any question.

[rbbeeston]

you can go ahead and merge this, please also test on staging.

[sdarwin]

@gavinwahl , please check this Github Actions result: https://github.com/boostorg/website-v2/actions/runs/11524519367

Database migrations failed.

"CommandError: Conflicting migrations detected; multiple leaf nodes in the migration graph: (0023_library_slug_unique_case_insensitive, 0023_libraryversion_authors in libraries)."