opam: move all opam files to the opam subdir (#6402)

This cleans up the root folder

It's unclear whether this change is compatible with how the docs
workflow uses setup-ocaml. I've updated it to use it the same way as the
other workflows (except it doesn't install the test dependencies)

This will need changes in the sync-xapi-metadata tool of xs-opam, but I
can fix that later

Author: psafont

.github/workflows/docs.yml

@@ -31,15 +31,23 @@ jobs:
       - name: Update Ubuntu repositories
         run: sudo apt-get update
 
+      # We set DUNE_CACHE_STORAGE_MODE, it is required for dune cache to work inside opam for now,
+      # otherwise it gets EXDEV and considers it a cache miss
       - name: Use ocaml
-        uses: ocaml/setup-ocaml@v2
+        uses: ocaml/setup-ocaml@v3
         with:
           ocaml-compiler: ${{ steps.dotenv.outputs.ocaml_version_full }}
           opam-repositories: |
             xs-opam: ${{ steps.dotenv.outputs.repository }}
+          dune-cache: true
+          opam-pin: false
+          cache-prefix: v3-${{ steps.system-info.outputs.name }}-${{ steps.system-info.outputs.release }}
+        env:
+          DUNE_CACHE_STORAGE_MODE: copy
 
       - name: Install dependencies
-        run: opam pin list --short | xargs opam install --deps-only -v
+        shell: bash
+        run: opam install . --deps-only -v
 
       - name: Generate xapi-storage docs
         run: |

dune-project

@@ -3,6 +3,7 @@
 (formatting (enabled_for ocaml))
 (using menhir 2.0)
 (using directory-targets 0.1)
+(opam_file_location inside_opam_directory)
 
 (cram enable)
 (implicit_transitive_deps false)