Validate all Azure examples/modules for compatibility with azurerm 4.0

[alexott]

I.e., this could affect us:

• https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/guides/4.0-upgrade-guide#specifying-subscription-id-is-now-mandatory
• https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/guides/4.0-upgrade-guide#azurerm_databricks_workspace_customer_managed_key
• https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/guides/4.0-upgrade-guide#azurerm_databricks_workspace

[r3stl355]

Hey @alexott, I can take this

[r3stl355]

List of examples to convert:

• adb-exfiltration-protection
• adb-external-hive-metastore
• adb-kafka
• adb-lakehouse
• postponedadb-overwatch: subject to outcome of [Discuss] Remove modules and examples for Overwatch #159
• adb-private-links
• postponedadb-squid-proxy: subject to outcome of [Discuss] Remove adb-squid-proxy example #163
• adb-teradata
• no change adb-uc: as it does not create a workspace
• no changeadb-unity-catalog-basic-demo: as it does not create a workspace
• adb-vnet-injection
• adb-with-private-link-standard
• adb-with-private-link-exfiltration-protection

As part of this exercise I suggest also updating the READMEs and aligning all the templates to use the same conventions, e.g. providers.tf instead of mix of versions.tf and providers.tf

[r3stl355]

I did not make any changes to network_security_group_rules_required as mentioned in azurerm_databricks_workspace. Testing a deployment with it added to ignore_changes resulted in a failing destroy so I didn't do it anywhere