Sync dune-project with opam dependencies (#8423)

* Sync dune-project with opam dependencies

The .opam files declared dependencies (cppo, flow_parser, ocamlformat,
yojson, ounit2, odoc, ocaml-lsp-server, js_of_ocaml,
wasm_of_ocaml-compiler) that were not present in dune-project. For the
rescript package those deps were sourced from rescript.opam.template,
which fully overrode what dune-project would have generated. For
analysis and tools, the odoc {with-doc} entry was missing entirely.

Move all dependencies into dune-project so it is the single source of
truth, and shrink rescript.opam.template to only the pin-depends: block
for the flow_parser fork — the one field dune-project cannot express.
The regenerated .opam files are equivalent to the previous ones.

* add dune