Draft: Bump nextcloud theme to 27.0.0

https://gitlab.e.foundation/e/infra/deployments/-/issues/396

Related to https://gitlab.e.foundation/e/infra/ecloud/nextcloud-apps/nextcloud-theme/-/pipelines/397555

Checklist

• Keep MR in Draft status
• Remove MR Draft status only after all app updates and theme updates in the Dockerfile have been tagged/released and final image is at staging
• Get app versions on server already: occ app:list
• Ensure that none of the versions in Dockerfile are downgraded
• Update app version using job id for apps including build steps
  • Once the job is tagged/released, update the job id again before final merge
• Update app version using branch name for apps without build steps
  • Once app is tagged/released, update app version using the correct tag
• Update the theme version
  • During development, use the branch name
  • Once theme is tagged/released, update image to use the correct tag
• Post deployment, get app versions again with occ app:list
  • Verify that no app was disabled during the upgrade process(if it was, understand why and add a suitable fix either to image or deployment process)

Adding a new app to image

• Add the correct version variable in Dockerfile are downgraded
• Extract app to the correct directory as per reference
• Add a correct rsync entry at reference
• Bump last number in version to ensure changes are copied over during update

Adding a new patch to image

• Add the patch in the patches subdirectory
• Add the patch command to Dockerfile
  • For a single file patch use reference
  • For a multi file patch use reference
• Bump last number in version to ensure changes are copied over during update

Coding Style and Guidelines

• https://gitlab.e.foundation/internal/wiki/-/wikis/development/Coding-Style-Cloud