Upgrade OpenDAL 0.45.1 -> 0.51.1 (#21835)

This continues #21779, working through the various breaking changes in
OpenDAL to upgrade from 0.45.1 to 0.51.1.

Among other things, this cuts out a bunch of duplicated dependencies,
yay, maybe faster builds.

Fixes #21764 (hopefully!), by removing the duplicated `reqwest`
dependency (see
#21764 (comment)
for analysis).

(Release notes from #21779 seem to cover this, hence no addition notes
in this PR.)