ci: better support PR from fork (#2670)

This applies to the "build preview" and the "references validation".

The content of the branch of the fork is now correctly used. Previously, the branch of the fork wasn't found by Antora, so the content of the generated site was empty.

### Notes

Covers
bonitasoft/bonita-documentation-site#402
This depends on
bonitasoft/bonita-documentation-site#698

.github/workflows/build-pr-preview.yml

@@ -9,17 +9,9 @@ on:
 jobs:
   validate_xref:
     runs-on: ubuntu-22.04
-    env:
-      COMPONENT_NAME: bonita
-      COMPONENT_BRANCH_NAME: ${{ github.head_ref }}
     steps:
       - name: Validate xref
         uses: bonitasoft/bonita-documentation-site/.github/actions/build-pr-site/@master
-        with:          
-          # '>' Replace newlines with spaces (folded)
-          # '-' No newline at end (strip)
-          build-preview-command: >-
-            ./build-preview.bash
-            --component "${{ env.COMPONENT_NAME }}"
-            --branch "${{ env.COMPONENT_BRANCH_NAME }}"
+        with:
+          component-name: bonita
           fail-on-warning: true