Key flow authentication (#67)

* Add key flow params to provider

* Update docs, add examples

docs/resources/objectstorage_bucket.md

@@ -0,0 +1,27 @@
+---
+# generated by https://github.com/hashicorp/terraform-plugin-docs
+page_title: "stackit_objectstorage_bucket Resource - stackit"
+subcategory: ""
+description: |-
+  ObjectStorage bucket resource schema.
+---
+
+# stackit_objectstorage_bucket (Resource)
+
+ObjectStorage bucket resource schema.
+
+
+
+<!-- schema generated by tfplugindocs -->
+## Schema
+
+### Required
+
+- `bucket_name` (String) The bucket name. It must be DNS conform.
+- `project_id` (String) STACKIT Project ID to which the bucket is associated.
+
+### Read-Only
+
+- `id` (String) Terraform's internal resource identifier. It is structured as "`project_id`,`bucket_name`".
+- `url_path_style` (String)
+- `url_virtual_hosted_style` (String)