azurerm_logic_app_standard - update resource to use go-azure-sdk …

…and add `public_network_access` (hashicorp#27913)

* migrate logic app standard to go-azure-sdk

* add public_network_access

* finish half baked logic app resource and data source documentation

* use helper to get and set site_credential

* deprecate site_config.public_network_access_enabled

* fix panic when site_config.public_network_access_enabled isn't set and add data source deprecation to upgrade guide

* use storage_account_id for storage share resource

* review comments