Add support for OCI tarball url

[migruiz4]

Description of the change

This PR aims to fix #8153 by resolving this error:

E1219 15:25:15.632218       1 utils.go:1024] Failed to import files, ID=bitnami/nginx, version=17.3.3: Get "oci://registry-1.docker.io/bitnamicharts/nginx:17.3.3": unsupported protocol scheme "oci"

Benefits

Currently, the kubeapps-asset-syncer is unable to fetch the information when the chart URL is stored in OCI.

In this PR, the chart tarballUrl is transformed when the oci schema is detected and replaced by its OCI blob URL, so the asset syncer will be able to fetch the chart tarball the same way as it does for non-OCI charts.

Possible drawbacks

None known.

Applicable issues

• fixes An error occurred while fetching the catalog: Unable to get the available package detail for the package "bitnami/mysql" using the plugin "helm.packages": internal: Unable to retrieve chart files: sql: no rows in result set.  #8153