[FEATURE] Configure External Delta Sharing for auto-generated metastores

[cjf-fuller]

Use-cases

We now use the auto-generated unity-catalog metastores but are unable to grant delta_sharing_scope on the auto-generated metastore which prevents us from creating external databricks_recipient resources through terrraform - we get the following error:

 Error: cannot create recipient: 
│ External Delta Sharing is not enabled on the metastore.
│ Please contact the account admin to enable External Delta Sharing."
│ 
│ 
│   with module.unity_common[0].module.ktl_data_services_share.databricks_recipient.recipient[0],
│   on ../../data_modules/datalake/unity/delta_share/delta_share.tf line 38, in resource "databricks_recipient" "recipient":
│   38: resource "databricks_recipient" "recipient" {
│ 

We can enable External Delta Sharing via the Databricks console but this is an additional manual step in our deployment which we're trying to automate as far as possible.

Attempted Solutions

Importing metastore as a databricks_metastore resource to alter the setting but terraform 1.5.x doesn't support dynamic import blocks and the metastore ID must be passed in as a string literal.

Proposal

Could External Delta Sharing be made configurable via terraform so we can apply it to auto-generated metastores that are not managed in IaC